Radio Interview: Sal Khan on NPR's Talk of the Nation (October 23, 2012)

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Language: en

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Neal: The scene is indelibly imprinted

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on anyone who's been to college:

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row after row of students gazing down

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as a professor or a TA drones on

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about chemical bonds or
the Byzantine Empire.

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The long lecture is widely accepted

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as an economical and effective way

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to educate large groups of students,

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but in a piece for Time Magazine,

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Salman Khan argues that even
the most brilliant speaker

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and the most compelling subject

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won't hold students' attention
for more than 18 minutes.

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So, call and tell us about
the lecture you remember best;

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800-989-8255; email us talk@npr.org.

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You could also join the
conversation on our website,

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that's at npr.org, click
on "Talk of the Nation."

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Salman Khan is founder
of the Khan Academy,

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author of "The One World
Schoolhouse: Education Reimagined,"

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and joins us now from his
studio in Stanford, California.

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Nice to have you with us today.

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Salman: Great to be here.

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Neal: What is it that makes
those lectures so boring?

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Salman: (chuckles) Well, I think all of us

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could answer that in a very anecdotal way,

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but what I think a lot
of people don't realize

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is that there's actually
been research in this base,

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to study the lecture,
and it's pretty decisive,

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it's never been really contradicted,

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that people can pay attention
for about 10-18 minutes,

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after which they start zoning out.

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Then they can kind of re-check
in for about 10 minutes,

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then they zone out for an
even longer period of time,

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and that keeps going on.

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Studies have shown that when
you do lecture at someone,

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that you actually retain some
of the early information,

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you retain very little of
the latter information.

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Just as you described,
a lot of the reason why

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we do it this way is really logistics;

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logistics coming from a
reality where we didn't have

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any other technologies to
deliver the information,

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so we, for the most part,
in colleges and K through 12

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around the world, we still
have a bunch of students

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sitting there for 60-90
minutes being lectured at.

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Neal: That vacillating
attention span you talk about,

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you could miss out on
entire pharaonic dynasties.

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Salman: (laughs) No, no,
that's exactly right.

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It hasn't gone completely unrecognized.

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There have been attempts
to address this issue.

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I talk about it in the book,
that there have been professors

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that try to do these change-ups,

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try to ask questions,

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try to do little group
things every 10 or 15 minutes

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to address this issue,

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but what I point out is that
that's a bit of a half-way fix.

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What we really should think
is well, is this class time,

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this time that all these
human beings get together,

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is lecture even the best use of that?

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Neal: Well, you've got to convey a certain

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amount of information
to, certainly in the case

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of college introduction
courses, a whole bunch

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of people at the same time.

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Salman. That's right, and
200 years ago I probably

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couldn't have come up with
a better way of doing that.

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Now we have very on-demand
ways to access media,

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obviously things like YouTube,

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obviously things like Khan
Academy what I work on,

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but there's other efforts.

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There's EdEx that MIT
and Harvard are doing.

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A lot of med schools have actually

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been doing this for a little while,

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where students are getting
the information delivery,

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the lecture, at their own time and pace.

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There are benefits to that
because you can pause.

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If there's a word you don't understand,

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you could look it up on the internet.

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You can go ask a friend.

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If you forgot a little bit
of your review material

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from a couple of years ago,
no need to be embarrassed

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and raise your hand in the middle of class

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and stop everyone's learning.

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You can go review that material,

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and you don't have to take notes

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because it's always there.

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Then when you go to class time,

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you can use that for
something more valuable

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like a conversation or a project

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or some type of peer-to-peer learning.

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Neal: But isn't it also the
student's responsibility

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to absorb some of this knowledge?

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Salman: It is, it is, and
it's always going to be

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the student's responsibility.

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In fact, I think that's
why lecture misses,

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is that at the end of the
day, learning is something

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that the student has to decide to do.

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At the university level, especially,

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I've always said it would
be interesting to administer

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a final exam 2 days
before students thought

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that they were going to get the final exam

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and see what the delta is.

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You'll see that very
little of the learning,

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or at least as measured by the final exam,

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occurs in the first 90% of the class.

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It's really the last 2-3
days before the exam,

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students are cramming
and teaching each other

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and that's what's really
moving the dial on their exams.

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Neal: I wonder, you said
you don't have to take notes

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if you can have electronic
copies of the lectures,

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digital copies that you
can go back and refer to.

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Doesn't the act of taking
notes help you learn?

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Salman: The act of doing
anything does help you learn.

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Fundamentally, if you
are passive in anything

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you're probably not that engaged.

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I think a lot of students do take notes

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literally just to stay awake,

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literally to be engaged.

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A lot of students say they
don't use the notes later on,

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it's just really to somewhat stay engaged.

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That's the whole point.

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If we want students to stay engaged,

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going through this
exercise of taking notes

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while listening to a lecture,

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and oftentimes not being able to listen

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because they're taking notes,

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let's just make it more active.

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Instead of doing these change-ups
every 10 or 15 minutes,

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let's make the whole classroom change-ups.

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Let's make the whole classroom
students teaching each other,

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students having a
conversation with each other.

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The one thing I point
out a lot in the book is

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we talk about this human
experience of education,

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but when students are
sitting in a classroom

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and there's someone lecturing at them,

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maybe they're taking notes,

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you're in a room with 30,
maybe 300 other people

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at the college level,

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that's a very dehumanizing experience.

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I've sat in classes for the whole semester

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and I didn't know 98% of those people,

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I didn't know their names.

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What we're really advocating,

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and we're starting to see in a
lot of schools and universities,

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is let's have those 300 people
interact with each other.

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Instead of having a study
group just the last 3 days

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before the exam, why don't we
have it for the whole semester?

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Neal: A study group with 300 people;

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that's not a class, it's a potential riot.

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Salman: (laughs) No, no, that's right.

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I think that's where
technology comes in, again.

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One, it can help deliver
some of the information

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that lectures used to do;

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but now you can also coordinate.

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You can see where students
are in their skill levels,

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you can pair them up,

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you can give diagnostics to the teacher.

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Some people say, "Well, students might not

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"listen to lecture if
it's happening at home."

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Before they had homework
that could have been checked.

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What I point out, and most
people agree with this,

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is that the homework,
or the problem solving,

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is where the learning is happening.

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If students are going to check out

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of one of the two things, I would say

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make sure it's not the problem solving.

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Neal: Going back to your
days as a student, though,

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are there lectures that you
remember particularly vividly?

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Salman: (chuckles) I
talk a lot in the book,

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my own experience in
undergrad, I talk about,

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I was a bit of a chronic class skipper.

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sometimes out of laziness,

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but for the most part it
was just out of finding

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the most productive use of my time.

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I discovered there was this whole world,

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this was at MIT,

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of people who never went to class

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and would use that time to
do problem solving instead.

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For the most part, the
ones that were memorable

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were the ones where there
was a shared experience.

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There were some great orators,

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some great lecturers that were inspiring,

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but it was good for moments.

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It wasn't great when you were trying

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to dig deep into something,

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when you might be a little bit lost

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and you want to catch up but
the class is going at a pace,

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you might be a little bit bored,

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you might know the material already.

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I think the shared experience of a lecture

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is great for inspirational things.

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It's great for things
that aren't super deep

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in terms of the substantive nature.

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I think those type of things can happen

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on-demand at your own pace,

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then class time is all
about problem solving.

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Neal: We're talking with Salman Khan,

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founder of the Khan Academy,

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a non-profit that creates
online educational videos.

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He's the author of

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"The One World Schoolhouse:
Education Reimagined."

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We want to hear today from you

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about the college lecture
you vividly remember,

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800-989-8255, email talk@npr.org.

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Benjamin's on the line
with us from Fort Wayne.

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Benjamin: Hi there.

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Neal: Hi.

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Benjamin: What I remember
out of all the lectures

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that I've had in college
is from my sociology class.

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Robert Pettit, he's a
great sociology teacher,

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he was using visuals
along with his speech,

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and he was teaching us about
socially constructed realities.

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Basically, he was petting an
invisible cat on his desk.

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Neal: (laughs)

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Benjamin: With saying, if we all believe

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there was a cat here, then
therefore it does exist.

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It was really interesting.

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I've found that incorporating
visuals with speaking

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made it easier to remember,
more likely to remember.

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Neal: Clearly you remember that one.

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How long ago was that?

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Benjamin: That was, I
would say, 2 years ago.

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Neal: That's not all that long ago.

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Benjamin: No, not at all.

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Neal: All right, thanks very
much for the phone call.

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Appreciate it.

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Benjamin: Thank you.

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Neal: So even some simple
devices, acting out

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and some visuals, Salman
Khan, can help somewhat.

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Salman: It sounds like that
was a great instructor,

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a great lecturer.

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What I would say is that actually

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he should share those skills,

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and it sounds like he was
humorous and all the rest,

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that instructor should make videos,

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put them online.

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His students could access them.

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Then when they go class,

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they can actually have
that debate about whether,

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if everyone believes the cat is there,

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whether it really is there.

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Neal: Let's see if we go to James.

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James is with us from
Montrose in Colorado.

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James: Hi Neal.

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Neal: Hi.

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James: I just wanted to share
really my most memorable

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and this little instance
was the only memory

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that I have of the entire
semester in this class.

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Neal: (chuckles)

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James: Physical geography,
where my professor

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was teaching for the first
time in America from China.

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Nobody could understand a word she said

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until she made one comment
about how she recently

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arrived in American and a
friend called her from China

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and she's trying to describe
the Earth's rotation

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around the sun and how days
and nights are different

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on different sides of the planet,

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and her friend says,
"Hi, how are you doing?"

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She said, "Well, how in the
hell do you think I'm doing?

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"It's 3 in the morning, I'm sleeping."

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That was the only bit
that me and probably 175

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other students caught
for 3-1/2 plus months.

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Neal: (laughs)

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Neal: How'd you do on the course?

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James: That was about 12-1/2 years ago.

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I want to say I did pretty well.

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I enjoyed the class, but honestly,

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I can't remember a lick of it.

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Neal: I guess, Salman Khan,

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thanks very much for the call, James,

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that makes your point.

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Salman: Yeah, that's exactly.

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Most of us can't remember
actually the courses we took,

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and I'm not that far out of college,

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much less the actual
content of a lot of it.

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Even when you were there,
running up to the final exam,

00:10:45.316 --> 00:10:47.737
this is why there are so
many students cramming,

00:10:47.737 --> 00:10:49.819
is that they've learned very little.

00:10:49.819 --> 00:10:50.996
They've gone through the motions.

00:10:50.996 --> 00:10:52.228
They feel like they're paying tuition.

00:10:52.228 --> 00:10:55.396
It's part of the, I guess the
ceremony of going to college,

00:10:55.396 --> 00:10:57.122
of showing up at these lectures

00:10:57.122 --> 00:10:58.817
because that seems to be
what everyone else is doing.

00:10:58.817 --> 00:11:00.814
But I've actually found that the students

00:11:00.814 --> 00:11:02.067
that are most productive are the ones

00:11:02.067 --> 00:11:04.123
that use that time to
go do something else.

00:11:04.123 --> 00:11:06.403
Neal: Email from Alan in Augusta, Georgia.

00:11:06.403 --> 00:11:08.496
"Of thousands of lectures I've enjoyed,

00:11:08.496 --> 00:11:10.396
"the best is no doubt Jack Pettigrew's

00:11:10.396 --> 00:11:12.403
"'Love is a Plastic State.'

00:11:12.403 --> 00:11:14.248
"I heard this as a student at his

00:11:14.248 --> 00:11:17.001
"neurophysiology class in Caltech in 1975,

00:11:17.001 --> 00:11:18.751
"but he delivered it elsewhere as well.

00:11:18.751 --> 00:11:21.416
"The point was to discuss
neuronal plasticity,

00:11:21.416 --> 00:11:22.853
"how our brains change,

00:11:22.853 --> 00:11:24.378
"and he illustrated it
with numerous anecdotes

00:11:24.378 --> 00:11:26.004
"including how his brother-in-law

00:11:26.004 --> 00:11:29.002
"lost his fear of a
deadly snake while high.

00:11:29.002 --> 00:11:31.239
"Jack really illuminated the subject,

00:11:31.239 --> 00:11:34.004
"the impact of evolution on brain states."

00:11:34.004 --> 00:11:36.985
We're talking with Salman
Khan about lectures

00:11:36.985 --> 00:11:38.500
and re-imagining them.

00:11:38.500 --> 00:11:42.565
You're listening to Talk of
the Nation from NPR News.

00:11:42.565 --> 00:11:44.404
Let's go next to Richard.

00:11:44.404 --> 00:11:46.260
Richard is with us from
Sioux City in Iowa.

00:11:46.260 --> 00:11:47.403
Richard: Hi, hello everybody.

00:11:47.403 --> 00:11:48.401
Nice program.

00:11:48.401 --> 00:11:48.983
Neal: Thank you.

00:11:48.983 --> 00:11:50.249
Richard: Thanks for having me on.

00:11:50.249 --> 00:11:52.998
I teach mindfulness and I
was in a mindfulness course

00:11:52.998 --> 00:11:55.499
at University of Missouri
quite a few years ago,

00:11:55.499 --> 00:11:56.872
a graduate-level course.

00:11:56.872 --> 00:11:59.735
The first lecture about mindfulness was,

00:11:59.735 --> 00:12:02.748
actually started with eating
a raisin and where we,

00:12:02.748 --> 00:12:04.814
the raisins were passed out.

00:12:04.814 --> 00:12:07.122
The idea is we're going
to focus our attention

00:12:07.122 --> 00:12:09.999
on all of the sensuous
aspects of the raisin

00:12:09.999 --> 00:12:11.239
before we even taste it,

00:12:11.239 --> 00:12:12.897
before we put it in our mouth.

00:12:12.897 --> 00:12:15.149
Mindfulness, as you may
know, is, of course,

00:12:15.149 --> 00:12:21.513
the entire process of controlling
your attentional awareness.

00:12:21.513 --> 00:12:25.042
The intent of mindfulness
is that we train our minds

00:12:25.042 --> 00:12:29.132
so that they don't drift away
or drift forward or drift back,

00:12:29.132 --> 00:12:32.747
and we do have more
disciplined thinking processes.

00:12:32.747 --> 00:12:35.379
Neal: Did it worked after 18
minutes or so with the raisin?

00:12:35.379 --> 00:12:36.589
Richard: (laughs) Yeah.

00:12:36.589 --> 00:12:38.016
I'd say with that course it really did

00:12:38.016 --> 00:12:39.259
because it was an 8-week course

00:12:39.259 --> 00:12:42.130
and it absolutely helps to discipline,

00:12:42.130 --> 00:12:44.435
again, your attentional awareness.

00:12:44.435 --> 00:12:46.380
Where is your attention
at this very moment?

00:12:46.380 --> 00:12:48.647
Is it where it should be or not?

00:12:48.647 --> 00:12:52.016
As a person who now prepares and teaches

00:12:52.016 --> 00:12:53.598
those programs for a couple of schools,

00:12:53.598 --> 00:12:55.873
I can tell you it does work.

00:12:55.873 --> 00:12:57.924
It may be something that
would be of interest

00:12:57.924 --> 00:13:00.257
or that your guests may already be,

00:13:00.257 --> 00:13:02.004
of which they may already be aware.

00:13:02.004 --> 00:13:04.470
Neal: Salman Khan, are
you aware of mindfulness?

00:13:04.470 --> 00:13:06.509
Salman: I think that example,

00:13:06.509 --> 00:13:09.008
the reason why it was so memorable

00:13:09.008 --> 00:13:11.735
is because the students
were doing something.

00:13:11.735 --> 00:13:13.508
They were observing the raisin.

00:13:13.508 --> 00:13:14.669
They were given an activity to do.

00:13:14.669 --> 00:13:16.508
They weren't just being lectured at.

00:13:16.508 --> 00:13:19.052
What I'm saying is that
lecture's invaluable.

00:13:19.052 --> 00:13:20.507
People have given some examples of some

00:13:20.507 --> 00:13:21.919
very memorable lectures they had.

00:13:21.919 --> 00:13:24.123
It's just that is that the best use

00:13:24.123 --> 00:13:25.503
of when humans get together?

00:13:25.503 --> 00:13:26.634
A lot of these very entertaining,

00:13:26.634 --> 00:13:28.029
very inspiring lectures ...

00:13:28.029 --> 00:13:31.171
I'm coming here as someone who's made

00:13:31.171 --> 00:13:32.755
3,000 lectures on YouTube.

00:13:32.755 --> 00:13:35.181
I'm not saying that they're not valuable,

00:13:35.181 --> 00:13:38.258
I'm just saying that they
could maybe be best used

00:13:38.258 --> 00:13:40.981
when you're not in the classroom.

00:13:40.981 --> 00:13:42.676
In the classroom, you
should do things like that,

00:13:42.676 --> 00:13:43.876
expose people to new experiences,

00:13:43.876 --> 00:13:45.000
make them think about it,

00:13:45.000 --> 00:13:46.258
have a two-way conversation.

00:13:46.258 --> 00:13:48.474
Richard: I agree because
in teaching mindfulness,

00:13:48.474 --> 00:13:51.481
I do have a didactic and
then an experiential portion.

00:13:51.481 --> 00:13:54.927
During the didactic portions
I do try to limit it

00:13:54.927 --> 00:13:57.591
to 12 minutes or so
because I know what happens

00:13:57.591 --> 00:13:59.113
and people don't pay attention.

00:13:59.113 --> 00:14:00.341
Neal: Interesting.

00:14:00.341 --> 00:14:01.349
Thanks very much for the call, Richard.

00:14:01.349 --> 00:14:02.049
Richard: Thank you.

00:14:02.049 --> 00:14:08.014
Neal: That amount of
time, is that time span,

00:14:08.014 --> 00:14:11.006
that ability to focus for 10-18 minutes,

00:14:11.006 --> 00:14:15.199
does that cover other aspects
of interaction as well?

00:14:15.199 --> 00:14:17.504
Salman: You know, I haven't
seen studies on that,

00:14:17.504 --> 00:14:19.998
but I would believe that
that's probably the case.

00:14:19.998 --> 00:14:23.130
Even in our organization,
we're not-for-profit,

00:14:23.130 --> 00:14:25.110
but there's 36 people who work with me,

00:14:25.110 --> 00:14:27.202
we kind of eat our own dog food.

00:14:27.202 --> 00:14:28.880
We say, look, if we ever have a meeting,

00:14:28.880 --> 00:14:30.882
no one should be talking
for more than 3 minutes.

00:14:30.882 --> 00:14:32.195
If you're talking for more than 3 minutes,

00:14:32.195 --> 00:14:33.486
it's a lecture, make a video,

00:14:33.486 --> 00:14:34.993
Neal: (laughs)

00:14:34.993 --> 00:14:37.625
and people can ask you
questions when we get together.

00:14:37.625 --> 00:14:40.258
Neal: So you have to do that as well.

00:14:40.258 --> 00:14:43.627
Then the space of these
interactive meetings,

00:14:43.627 --> 00:14:46.759
presumably people could
concentrate a little longer.

00:14:46.759 --> 00:14:51.386
Salman: We've all had
hours-long conversations

00:14:51.386 --> 00:14:52.504
and enjoyed ourselves.

00:14:52.504 --> 00:14:53.977
That's actually where we learned a lot.

00:14:53.977 --> 00:14:55.028
A lot of what we learn from is from

00:14:55.028 --> 00:14:56.646
conversations with other people

00:14:56.646 --> 00:14:59.828
That, obviously, can go on well beyond

00:14:59.828 --> 00:15:01.165
10 minutes or even an hour

00:15:01.165 --> 00:15:02.910
because you are actively engaged,

00:15:02.910 --> 00:15:04.214
your brain is actively processing

00:15:04.214 --> 00:15:05.761
and thinking of new things.

00:15:05.761 --> 00:15:07.383
Neal: Let's see, we
get one more caller in.

00:15:07.383 --> 00:15:08.673
This is Jennifer.

00:15:08.673 --> 00:15:10.587
Jennifer's on the line
with us from Orange County.

00:15:10.587 --> 00:15:11.625
Jennifer: Hello.

00:15:11.625 --> 00:15:12.500
Neal: Hi Jennifer.

00:15:12.500 --> 00:15:14.011
Jennifer. Hi.

00:15:14.011 --> 00:15:17.301
I had a Disability and Society class,

00:15:17.301 --> 00:15:19.800
actually it was a psychology class,

00:15:19.800 --> 00:15:22.308
in undergrad and I really
remember very little

00:15:22.308 --> 00:15:24.005
from undergraduate school.

00:15:24.005 --> 00:15:28.668
There was a guest speaker
who had cerebral palsy.

00:15:28.668 --> 00:15:33.501
It was my first experience
really hearing from a person

00:15:33.501 --> 00:15:35.366
who had cerebral palsy.

00:15:35.366 --> 00:15:39.370
Before that, I had no
idea that their brains

00:15:39.370 --> 00:15:40.938
functioned exactly the same way

00:15:40.938 --> 00:15:42.885
that a normal person's functions,

00:15:42.885 --> 00:15:44.774
it was just their muscles and their bodies

00:15:44.774 --> 00:15:45.885
didn't work the same

00:15:45.885 --> 00:15:47.599
and they weren't able to
communicate the same way.

00:15:47.599 --> 00:15:49.769
Being in that room,

00:15:49.769 --> 00:15:52.633
there was probably over
200 people in that lecture,

00:15:52.633 --> 00:15:57.024
but the professor did such an amazing job

00:15:57.024 --> 00:16:00.635
of bringing people in
and engaging the class

00:16:00.635 --> 00:16:05.126
and changing perspectives.

00:16:05.126 --> 00:16:08.867
Another thing that she did is she had us,

00:16:08.867 --> 00:16:11.703
in the midst of our lecture,

00:16:11.703 --> 00:16:15.553
walk around campus and picture
ourselves in a wheelchair,

00:16:15.553 --> 00:16:17.350
and then come back to the room

00:16:17.350 --> 00:16:19.245
and talk about what that
might have been like

00:16:19.245 --> 00:16:20.486
if we actually were in a wheelchair

00:16:20.486 --> 00:16:21.885
and how we would have gotten around.

00:16:21.885 --> 00:16:22.950
Neal: So experiencing something,

00:16:22.950 --> 00:16:25.382
as well as just being lectured to.

00:16:25.382 --> 00:16:26.879
Jennifer, thanks very much for your time.

00:16:26.879 --> 00:16:28.178
Jennifer: Thank you.

00:16:28.178 --> 00:16:29.497
Neal: One last email.

00:16:29.497 --> 00:16:30.894
This from Janice in Scottsdale.

00:16:30.894 --> 00:16:33.262
"A professor of philosophy
at Eisenhower College

00:16:33.262 --> 00:16:34.360
"in Seneca Falls, New York

00:16:34.360 --> 00:16:36.619
"was assigned the day's
world studies lecture

00:16:36.619 --> 00:16:38.990
"to our sophomore class,
approximately 100 students.

00:16:38.990 --> 00:16:40.534
"The topic was Zen Buddhism.

00:16:40.534 --> 00:16:41.788
"He went up to the podium

00:16:41.788 --> 00:16:43.616
"and stood there in
complete and utter silence,

00:16:43.616 --> 00:16:45.594
"looking at us for 50 minutes."

00:16:45.594 --> 00:16:48.999
Salman Khan, thanks very much
for your time today, too.

00:16:48.999 --> 00:16:49.649
Salman: Thanks for having me.

00:16:49.649 --> 00:16:53.500
Neal: It's the Talk of
the Nation from NPR News.


Radio Interview: Sal Khan on Brian Lehrer (Oct 4, 2012)

WEBVTT
Kind: captions
Language: en

00:00:00.725 --> 00:00:04.989
Voiceover: Most viral videos
involve like a baby panda sneezing,

00:00:05.035 --> 00:00:08.124
or a Korean pop star's
infectious silly dance,

00:00:08.124 --> 00:00:12.241
but in 2004, hedge fund
analyst, Salman Khan -

00:00:12.241 --> 00:00:16.278
this is not the Bollywood star, by the
way, Salman Khan, for you Bollywood fans;

00:00:16.278 --> 00:00:20.919
this is a different Salman
Khan - discovered that the
video tutorials he had made

00:00:20.919 --> 00:00:26.427
to explain algebra to his
12-year-old niece became
unexpectedly popular on YouTube.

00:00:26.427 --> 00:00:31.264
A couple of years later, he left the world
of finance to found the Khan Academy,

00:00:31.264 --> 00:00:34.099
an educational organization
that today provides

00:00:34.099 --> 00:00:39.640
over 3,000 free video lectures
and companion exercises online.

00:00:39.640 --> 00:00:42.706
Six years and almost two
hundred million views later,

00:00:42.706 --> 00:00:45.637
Khan has a plan to reform the classroom,

00:00:45.637 --> 00:00:51.390
which he outlines in his new
book, "The One World School
House, Education Reimagined."

00:00:51.390 --> 00:00:52.536
He joins us now.

00:00:52.536 --> 00:00:54.710
We'll play a couple of his
video excerpts in a minute.

00:00:54.710 --> 00:00:57.292
Salman Khan, welcome to WNYC.

00:00:57.292 --> 00:00:58.619
Voiceover: It's great to be here.

00:00:58.619 --> 00:01:01.728
Voiceover: At what point did you
transition from running the Khan Academy,

00:01:01.728 --> 00:01:03.459
creating and sharing these videos,

00:01:03.459 --> 00:01:06.991
to advocating for a major reform
of the educational process?

00:01:06.991 --> 00:01:13.637
Voiceover: There was never
a hard line when it started,
through this whole adventure,

00:01:13.637 --> 00:01:16.990
first working with my cousins,
then the YouTube videos,

00:01:16.990 --> 00:01:20.405
and then eventually getting
funding for this not-for-profit,

00:01:20.405 --> 00:01:21.982
and building up the interactive exercises,

00:01:21.982 --> 00:01:24.811
we've been interfacing a
lot with the school system,

00:01:24.811 --> 00:01:28.835
famously, the Los Altos school district
in northern California started using us.

00:01:28.835 --> 00:01:32.896
When they asked for ideas, I said it
seems like there's an opportunity here

00:01:32.896 --> 00:01:35.877
to not focus class time
on lecture anymore,

00:01:35.877 --> 00:01:37.625
and instead use it for interactivity.

00:01:37.625 --> 00:01:40.094
The lecture can happen in the
student's own time and pace.

00:01:40.094 --> 00:01:42.763
We can go to the self-paced reality.

00:01:42.763 --> 00:01:45.122
It, frankly, worked out
well for all involved,

00:01:45.122 --> 00:01:47.984
and we started experimenting
with other schools.

00:01:47.984 --> 00:01:54.176
Then, researchers, education
historians started coming up
to me and the rest of our team.

00:01:54.176 --> 00:01:56.429
Actually, there's a lot of
research that backs this up.

00:01:56.429 --> 00:01:57.926
It's called mastery-based learning.

00:01:57.926 --> 00:02:01.514
The way that we traditionally learn,
where these students are grouped

00:02:01.514 --> 00:02:03.372
in these age-based cohorts,

00:02:03.372 --> 00:02:05.760
this is not how humans
have always learned.

00:02:05.760 --> 00:02:10.122
We've inherited this from Prussia, a
nation that does not exist anymore.

00:02:10.122 --> 00:02:11.622
I go into depth about that in the book.

00:02:11.622 --> 00:02:13.505
Voiceover: Good old Prussia.

00:02:13.505 --> 00:02:18.510
Voiceover: It seemed like some
of these old but proven ideas

00:02:18.510 --> 00:02:20.757
about mastery-based learning,
about self-paced learning,

00:02:20.757 --> 00:02:24.777
could now be implemented in a
practical way, using the technology.

00:02:24.777 --> 00:02:27.423
Voiceover: Is this what you call
Swiss-cheese learning in the book?

00:02:27.423 --> 00:02:32.195
Voiceover: Yeah, once again, the
Prussia model had a positive motive.

00:02:32.195 --> 00:02:35.057
It was the first time that people
said, "How do we educate everyone?"

00:02:35.057 --> 00:02:37.472
If you go 300 years ago,
only the elite got educated.

00:02:37.472 --> 00:02:40.129
When they thought about
that problem, they said,

00:02:40.129 --> 00:02:41.625
"Well, it's the Industrial Revolution.

00:02:41.625 --> 00:02:43.482
"How do we make a lot of anything?

00:02:43.482 --> 00:02:44.877
"We put 'em on a line.

00:02:44.877 --> 00:02:46.345
"It moves at a pace.

00:02:46.345 --> 00:02:47.956
"At each station, something happens.

00:02:47.956 --> 00:02:48.907
"Some of the product is good.

00:02:48.907 --> 00:02:50.160
"Some of the product isn't so good."

00:02:50.160 --> 00:02:52.981
So, they applied the same
principles to educating children -

00:02:52.981 --> 00:02:56.409
big batches of kids,
throw knowledge at them.

00:02:56.409 --> 00:02:57.653
Some of them will get it.

00:02:57.653 --> 00:02:58.754
Some of them won't.

00:02:58.754 --> 00:03:00.128
What's happening with the Swiss cheese is

00:03:00.128 --> 00:03:01.655
as they go at that set
pace, it just accumulates.

00:03:01.655 --> 00:03:05.745
That's why you see, I think,
otherwise very capable kids,

00:03:05.745 --> 00:03:07.259
they get to algebra, they get to calculus,

00:03:07.259 --> 00:03:08.919
and they just hit a wall.

00:03:08.919 --> 00:03:11.124
Instead, we say, "No,
work at your own pace.

00:03:11.124 --> 00:03:12.424
"Master concepts.

00:03:12.424 --> 00:03:15.755
"Once you master concepts, then the
next concept's going to seem intuitive."

00:03:15.755 --> 00:03:18.252
Voiceover: As we mis
European metaphors here -

00:03:18.252 --> 00:03:20.256
the Prussian model, the
Swiss-cheese learning -

00:03:20.256 --> 00:03:25.003
here's a small taste of
what Salman Khan does.

00:03:25.003 --> 00:03:28.367
This is a clip from a video
posted just last week,

00:03:28.367 --> 00:03:31.011
and I should mention it has
almost 10,000 views already,

00:03:31.011 --> 00:03:35.377
and it explains probability
with a Monte Carlo simulation.

00:03:35.377 --> 00:03:41.096
This is about a minute long and
it begins with a special guest.

00:03:41.128 --> 00:03:43.002
Basketball fans, listen up.

00:03:43.002 --> 00:03:44.496
Voiceover: It's LeBron here.

00:03:44.496 --> 00:03:45.755
I've got a quick brain-teaser for you.

00:03:45.755 --> 00:03:48.250
If I'm down three, with 30 seconds left,

00:03:48.250 --> 00:03:50.123
is it better to take the three,

00:03:50.123 --> 00:03:52.252
or is it easier to take the two

00:03:52.252 --> 00:03:56.127
and attempt to foul a bad free-throw
shooter, and get another possession?

00:03:56.127 --> 00:03:59.910
"Here's my friend Sal with an answer."

00:03:59.910 --> 00:04:02.966
Voiceover: That's a very, very
interesting question, LeBron.

00:04:02.966 --> 00:04:05.713
Calculating the probabilities
of if you were to take a three,

00:04:05.713 --> 00:04:08.930
what's your probability of tying the game
and then being able to win in overtime?

00:04:08.930 --> 00:04:12.106
That can be done on paper, but
the scenario where you take a two,

00:04:12.106 --> 00:04:14.276
and you attempt to foul the opposing team,

00:04:14.276 --> 00:04:16.527
and they might make none,
or one or two free throws,

00:04:16.527 --> 00:04:18.986
and then you might get another
possession and you take another two,

00:04:18.986 --> 00:04:20.603
that's more complicated.

00:04:20.603 --> 00:04:21.779
You could attempt to do it on paper,

00:04:21.779 --> 00:04:24.744
but instead I've written a
little computer simulation here.

00:04:24.744 --> 00:04:27.543
This type of a simulation is
called a Monte Carlo simulation.

00:04:27.543 --> 00:04:29.776
Literally, it'll run the scenarios.

00:04:29.776 --> 00:04:33.089
It'll do it as many times as we
put in this variable over here.

00:04:33.089 --> 00:04:35.194
We're gonna set it up so
we get an accurate number.

00:04:35.194 --> 00:04:37.780
We're going to do it a thousand
times for each of those scenarios,

00:04:37.780 --> 00:04:42.273
and see what fraction in each scenario,
which fraction do we end up winning?

00:04:42.273 --> 00:04:45.380
Voiceover: So, a sample
of a Salman Khan video.

00:04:45.380 --> 00:04:50.027
If you can deconstruct yourself a little
bit, other than getting people's attention

00:04:50.027 --> 00:04:53.135
by using LeBron James,
what's the technique in there

00:04:53.135 --> 00:04:55.771
that makes it more
user-friendly than other things?

00:04:55.771 --> 00:05:00.130
Voiceover: When I started
these, it was for my cousins,

00:05:00.130 --> 00:05:02.089
and I didn't really
think about it too much.

00:05:02.089 --> 00:05:04.480
I just said, "Well, it's for my cousin.

00:05:04.480 --> 00:05:07.313
"I'll just do these somewhat
informally, very conversationally."

00:05:07.313 --> 00:05:11.011
I didn't show my face, because
I didn't feel like I needed to.

00:05:11.011 --> 00:05:13.796
I was already tutoring my cousins,
and they just heard my voice

00:05:13.796 --> 00:05:15.484
and we could see what we were writing.

00:05:15.484 --> 00:05:18.697
Later, we've gotten a lot
of feedback from people,

00:05:18.697 --> 00:05:21.195
and that's why we've tried not
to diverge too much from that,

00:05:21.195 --> 00:05:23.286
that they really liked this form factor.

00:05:23.286 --> 00:05:27.535
They didn't feel like there was
someone distant at a chalkboard saying,

00:05:27.535 --> 00:05:28.880
"Oh, the next step is XYZ"

00:05:28.880 --> 00:05:30.945
It felt like we were at
the kitchen table together.

00:05:30.945 --> 00:05:33.232
They felt like I was an
older brother or a cousin,

00:05:33.232 --> 00:05:35.198
explaining these types of ideas.

00:05:35.198 --> 00:05:38.379
We tried to retain that,
that conversationality,

00:05:38.379 --> 00:05:42.900
the humanity in it, the
connection with the learner.

00:05:42.900 --> 00:05:44.497
Voiceover: Listeners,
if you want to call in,

00:05:44.497 --> 00:05:46.997
we can take a few phone
calls for Salman Khan.

00:05:46.997 --> 00:05:49.151
I see some people are already calling in,

00:05:49.151 --> 00:05:53.153
who want to do testimonials, that
they've been using the system.

00:05:53.153 --> 00:05:59.939
So, 212-433-WNYC, if you
want to talk to Salman Khan.

00:05:59.939 --> 00:06:04.767
His new book is called, "The One World
School House, Education Reimagined."

00:06:04.767 --> 00:06:09.761
212-433-9692, and Miguel in
Queens, you're on the air.

00:06:09.761 --> 00:06:11.041
Hi, Miguel.

00:06:11.041 --> 00:06:14.015
Voiceover: Hi, how are you,
Ryan, and hello, Mr. Khan.

00:06:14.015 --> 00:06:17.122
I just want to let you
know that I understand

00:06:17.122 --> 00:06:19.511
why the video, the
first video, went viral.

00:06:19.511 --> 00:06:25.307
I'm going to college at night, and I feel

00:06:25.307 --> 00:06:30.306
that the professors just want
to go through the whole program,

00:06:30.306 --> 00:06:34.260
so they actually explained all.

00:06:34.260 --> 00:06:35.540
They just go through the class very fast.

00:06:35.540 --> 00:06:42.638
If I don't understand something,
and I want them to explain it again,

00:06:42.638 --> 00:06:48.313
they will explain one time, but
then they just [unintelligible] -

00:06:48.313 --> 00:06:54.378
Voiceover: So you went to some Salman Khan
videos that dealt with the same material?

00:06:54.378 --> 00:06:59.040
Voiceover: Yes, I went on
Youtube and looked for videos

00:06:59.040 --> 00:07:02.498
so I could understand my calculus
classes, Calculus I and 2.

00:07:02.498 --> 00:07:08.379
Because I was able to see it
once, and again and again,

00:07:08.379 --> 00:07:12.517
I was able to understand and
actually pass the classes.

00:07:12.517 --> 00:07:16.766
Voiceover: That's great, Miguel,
and I'm sure that warms your heart.

00:07:16.766 --> 00:07:20.262
Voiceover: Stories like Miguel's,
for myself and the rest of our team,

00:07:20.262 --> 00:07:21.712
that's what keeps us going.

00:07:21.712 --> 00:07:27.265
Voiceover: Are you like the
SparkNotes of YouTube, in a way?

00:07:27.265 --> 00:07:31.130
If people are not getting it on their
own, they can go get a quick tutorial?

00:07:31.130 --> 00:07:34.182
Voiceover: Yeah, but there's
one thing about that comparison

00:07:34.182 --> 00:07:36.763
that I think isn't completely there,

00:07:36.763 --> 00:07:39.755
which would be whenever people
think about ten-minute videos,

00:07:39.755 --> 00:07:40.996
they think, "Oh, maybe
this is the SparkNotes

00:07:40.996 --> 00:07:42.472
"or the Cliff Notes of mathematics."

00:07:42.472 --> 00:07:44.634
What I always point out
is that we can do as many

00:07:44.634 --> 00:07:46.049
of these 10-minute videos as we want,

00:07:46.049 --> 00:07:50.354
so we're not limited by 50 minutes
or 90 minutes in a lecture hall.

00:07:50.354 --> 00:07:55.897
What we get a lot of feedback from
students on is that we go into depth.

00:07:55.897 --> 00:07:57.523
We have a lot of examples.

00:07:57.523 --> 00:08:00.371
We go into the proofs, the conceptual
"how does it apply to the real world?"

00:08:00.371 --> 00:08:04.270
Voiceover: When you try to use
this, not just in this way,

00:08:04.270 --> 00:08:06.543
but as a model for reforming education,

00:08:06.543 --> 00:08:09.407
part of your concept is
called the flipped classroom.

00:08:09.407 --> 00:08:10.383
Explain.

00:08:10.383 --> 00:08:11.907
Voiceover: It's not my concept, actually.

00:08:11.907 --> 00:08:14.152
Very few of the concepts in
the book are new concepts.

00:08:14.152 --> 00:08:15.282
They're re-invigorated concepts.

00:08:15.282 --> 00:08:18.004
This is in the early days when
it's mainly the videos out there.

00:08:18.004 --> 00:08:20.943
I had teachers coming to me, emailing me,

00:08:20.943 --> 00:08:22.138
Saying, "Hey, look.

00:08:22.138 --> 00:08:25.864
"You've already given an
interesting lecture about
probability or about calculus.

00:08:25.864 --> 00:08:30.645
"Why should I use my scarce class time
to do this one-pace kind of lecture,

00:08:30.645 --> 00:08:32.319
"and the students are
sitting there passively?

00:08:32.319 --> 00:08:35.985
"Instead, they can watch your stuff
at their own time and their own pace,

00:08:35.985 --> 00:08:38.725
and then we can use class time
for something more interactive."

00:08:38.725 --> 00:08:41.811
Once again, the flip idea existed
before us, but what I did is,

00:08:41.811 --> 00:08:45.529
what used to be homework is now
class work, problem solving,

00:08:45.529 --> 00:08:47.141
and now you have your peers
and the teacher to help you.

00:08:47.141 --> 00:08:50.334
What used to be class time, which
is lectures, you get on demand.

00:08:50.334 --> 00:08:51.505
You can remediate.

00:08:51.505 --> 00:08:52.884
We think you can go even further.

00:08:52.884 --> 00:08:54.379
In the book, I go into a lot of depth,

00:08:54.379 --> 00:08:55.797
how you can go much beyond,
even doing the flip.

00:08:55.797 --> 00:08:56.755
Voiceover: Such as?

00:08:56.755 --> 00:08:59.047
Voiceover: Even the flip assumes
kind of a Prussian model,

00:08:59.047 --> 00:09:00.543
that we're all going to be learning

00:09:00.543 --> 00:09:02.388
at the same pace, the same
thing, at the same time.

00:09:02.388 --> 00:09:05.389
As soon as you remove
the one-pace-fits-all
lecture from the classroom,

00:09:05.389 --> 00:09:10.269
you say, "Well, maybe we could
have two teachers in the classroom
teaching twice as many students.

00:09:10.269 --> 00:09:14.230
"Maybe we could have every student
learning at their own pace,

00:09:14.230 --> 00:09:16.487
"breaking away from this
assembly-line model.

00:09:16.487 --> 00:09:19.014
"Maybe we could have students
start to tutor each other.

00:09:19.014 --> 00:09:21.123
"Maybe this opens up time for creativity,

00:09:21.123 --> 00:09:22.747
so they can do more open-ended projects."

00:09:22.747 --> 00:09:25.693
Voiceover: Keith in
Washington Heights calling

00:09:25.693 --> 00:09:28.866
with, I think, a little bit of
skepticism about the flip classroom.

00:09:28.866 --> 00:09:30.380
Yes, Keith?

00:09:30.380 --> 00:09:31.861
Voiceover: Good morning, gentlemen.

00:09:31.861 --> 00:09:34.456
I first heard about this
Khan Academy on "60 Minutes,"

00:09:34.456 --> 00:09:39.832
and they showed it in a classroom, where
the kids were learning from Khan Academy,

00:09:39.832 --> 00:09:41.991
and then the teacher would
circulate around the room

00:09:41.991 --> 00:09:43.572
for anybody that needed additional help.

00:09:43.572 --> 00:09:45.570
Don't get me wrong.

00:09:45.570 --> 00:09:48.116
I think the idea is great, and I've
watched a number of your videos there.

00:09:48.116 --> 00:09:51.355
I don't think you can
replace the teacher because,

00:09:51.355 --> 00:09:55.880
even when you're teaching your cousin,

00:09:55.880 --> 00:09:58.274
if you're on the phone with her
and talking to her directly,

00:09:58.274 --> 00:09:59.875
and having interaction back and forth,

00:09:59.875 --> 00:10:01.639
when she says, "I got that point.

00:10:01.639 --> 00:10:03.261
"Move on," or, "I don't have this point.

00:10:03.261 --> 00:10:05.764
"Repeat it," somehow it's different.

00:10:05.764 --> 00:10:07.623
Let me explain it better.

00:10:07.623 --> 00:10:08.849
Let me explain it differently.

00:10:08.849 --> 00:10:11.178
When I'm teaching my
students, I have interaction.

00:10:11.178 --> 00:10:13.210
I stop at each point.

00:10:13.210 --> 00:10:14.030
"Do we get it?

00:10:14.030 --> 00:10:14.916
"Do we not get it?

00:10:14.916 --> 00:10:15.910
"Who doesn't get it?

00:10:15.910 --> 00:10:16.783
"What needs to be further explained?"

00:10:16.783 --> 00:10:19.649
There's something lost when
you're just doing it on a video.

00:10:19.649 --> 00:10:21.489
It's great stuff, but
it's not the same thing

00:10:21.489 --> 00:10:25.949
as having a teacher explaining
it directly, and having an
interaction with the kids.

00:10:25.949 --> 00:10:27.281
Voiceover: Keith, thank you.

00:10:27.281 --> 00:10:27.635
Salman.

00:10:27.635 --> 00:10:29.509
Voiceover: I a hundred
percent agree with Keith.

00:10:29.509 --> 00:10:32.101
Actually, that was a
big point of this book,

00:10:32.101 --> 00:10:36.080
is whenever people come up with
something virtual, the assumption is,

00:10:36.080 --> 00:10:39.760
"Oh, this is going to compete
with the physical" - Amazon.com
versus Barnes and Noble's.

00:10:39.760 --> 00:10:44.415
Everything that we emphasize
is, what we are doing is a tool

00:10:44.415 --> 00:10:46.246
for students and for teachers.

00:10:46.246 --> 00:10:50.408
What it is, it allows class time to
be less based on a passive lecture,

00:10:50.408 --> 00:10:55.523
and more of the things that Keith just
talked about, more of the interaction.

00:10:55.523 --> 00:10:59.365
When my cousins were able to
do the exercises on their own
and the videos on their own,

00:10:59.365 --> 00:11:02.970
when they had time with me, I didn't
have to do any explaining to them,

00:11:02.970 --> 00:11:05.870
or I had to just fill in the gaps
that the videos didn't cover.

00:11:05.870 --> 00:11:07.269
So, I a hundred percent agree.

00:11:07.269 --> 00:11:08.280
I have young children.

00:11:08.280 --> 00:11:10.019
I do not want them to
learn only from a computer.

00:11:10.019 --> 00:11:12.471
I want that to actually be a very
small fraction of their learning.

00:11:12.471 --> 00:11:16.129
Voiceover: You were talking before
about a possible multi-teacher model

00:11:16.129 --> 00:11:18.044
in the classroom while
they're using the visuals.

00:11:18.044 --> 00:11:22.247
Have you costed out what
it would take financially

00:11:22.247 --> 00:11:26.179
to use this as a
nationally-scaleable model?

00:11:26.179 --> 00:11:28.426
Maybe you saw President Obama
in the debate last night,

00:11:28.426 --> 00:11:31.384
talking about that teacher
with the 42-student classroom.

00:11:31.384 --> 00:11:34.024
We're already strapped, in other words.

00:11:34.024 --> 00:11:36.374
Voiceover: Yeah, we're already
strapped and, obviously,

00:11:36.374 --> 00:11:38.510
even an extra penny is
going to cost something.

00:11:38.510 --> 00:11:41.066
Technology is getting cheaper every year.

00:11:41.066 --> 00:11:43.681
I don't think you even need
one computer per child.

00:11:43.681 --> 00:11:45.510
You could have one computer,
because they're not going

00:11:45.510 --> 00:11:46.983
to be spending all day on the computer.

00:11:46.983 --> 00:11:49.363
A computer's now two or
three hundred dollars.

00:11:49.363 --> 00:11:54.215
A new laptop or tablet device
can last four or five years,

00:11:54.215 --> 00:11:55.702
and be shared by four or five students.

00:11:55.702 --> 00:11:59.637
Really, it starts becoming on the order
of ten, twenty dollars a student a year.

00:11:59.637 --> 00:12:03.498
I think it becomes
cost-competitive with textbooks,

00:12:03.498 --> 00:12:07.918
which I really think is where this
could be more of a substitute,

00:12:07.949 --> 00:12:10.138
not for the teacher, but for the textbook.

00:12:10.138 --> 00:12:11.637
Voiceover: Now, you've
got people's attention,

00:12:11.637 --> 00:12:14.138
because everybody wants to
replace those expensive textbooks,

00:12:14.138 --> 00:12:17.359
that also get updated every few years
and you have to keep buying them.

00:12:17.359 --> 00:12:21.365
Dan in Brooklyn, we have time
for one more testimonial,

00:12:21.365 --> 00:12:22.996
and it'll come from Dan.

00:12:22.996 --> 00:12:24.250
Hi, Dan.

00:12:24.250 --> 00:12:27.387
Voiceover: Hi, I just want
to say as a neurobiologist

00:12:27.387 --> 00:12:31.639
that I really want to thank you for
saving the brains of so many children.

00:12:31.639 --> 00:12:33.827
Really, what people don't realize is

00:12:33.827 --> 00:12:37.305
that the brain proliferates
with connections and songs

00:12:37.305 --> 00:12:42.993
from the age one onward
to about 12, 13 years old.

00:12:42.993 --> 00:12:47.143
Then, it crashes and a lot of brain
cells and brain connections are lost -

00:12:47.143 --> 00:12:48.639
about 30% of them.

00:12:48.639 --> 00:12:54.637
What you're doing is making available
to children conceptual operations

00:12:54.637 --> 00:12:58.462
that will keep those
connections vibrant and alive.

00:12:58.462 --> 00:13:01.711
That's the European way of teaching
so that, right after high school,

00:13:01.711 --> 00:13:03.389
they go right to professional school -

00:13:03.389 --> 00:13:07.052
no wasting four years of college that make
up for 12 lost years of public education.

00:13:07.052 --> 00:13:09.389
Voiceover: Is that part of your goal,

00:13:09.389 --> 00:13:11.636
right on to professional
school from high school?

00:13:11.636 --> 00:13:13.197
Voiceover: That's not the goal.

00:13:13.197 --> 00:13:16.517
It's not NOT the goal either.

00:13:16.517 --> 00:13:20.064
The goal is actually to introduce
more variety into the system.

00:13:20.064 --> 00:13:21.536
In the book, I go into some detail -

00:13:21.536 --> 00:13:27.340
this 12 years of primary and secondary,
and you learn physics your senior year.

00:13:27.384 --> 00:13:30.811
This was determined in 1892 by ten men,

00:13:30.811 --> 00:13:33.570
mainly university presidents,
the Committee of Ten.

00:13:33.570 --> 00:13:37.374
I think it's time that we re-think
this 200-year-old Prussian model.

00:13:37.374 --> 00:13:40.755
It's time we re-think this 120-year-old
Committee of Ten proposition.

00:13:40.755 --> 00:13:43.636
It doesn't have to be exactly
what the caller is saying,

00:13:43.636 --> 00:13:45.866
but it doesn't have to be
exactly what we're saying now.

00:13:45.866 --> 00:13:47.120
It can be more flexible.

00:13:47.120 --> 00:13:49.465
Voiceover: Salman Khan -
he's an inspiration to many.

00:13:49.465 --> 00:13:54.499
His new book is called, "The One World
School House, Education Reimagined."

00:13:54.499 --> 00:13:57.639
By the way, you can access
all the Khan Academy materials

00:13:57.639 --> 00:14:01.037
online at Khan Academy dot org.

00:14:01.037 --> 00:14:02.385
Great to speak with you.

00:14:02.385 --> 00:14:03.047
Thank you for coming in.

00:14:03.047 --> 00:14:04.292
Voiceover: Thanks for having me.

00:14:04.292 --> 00:14:07.000
Voiceover: Right, we're at WNYC.


Sal Khan on CNN Starting Point (Oct 5, 2012)

WEBVTT
Kind: captions
Language: en

00:00:02.565 --> 00:00:04.440
SALMAN KHAN: Now that
students can get access

00:00:04.440 --> 00:00:07.709
to the information delivery part
of learning-- the lectures--

00:00:07.709 --> 00:00:09.250
at their own time
and their own pace,

00:00:09.250 --> 00:00:11.125
and we also have an
interactive portion where

00:00:11.125 --> 00:00:13.310
they can do problems,
a lot of teachers

00:00:13.310 --> 00:00:15.560
are saying, well, why should
I use the scarce class

00:00:15.560 --> 00:00:19.590
time for this kind of passive,
I lecture, people listen, take

00:00:19.590 --> 00:00:20.290
notes?

00:00:20.290 --> 00:00:22.210
Instead, we could use that
for actual interactivity.

00:00:22.210 --> 00:00:23.600
And it's different
for every teacher.

00:00:23.600 --> 00:00:25.180
It's different for
every classroom.

00:00:25.180 --> 00:00:27.900
But we've seen classrooms now
where when they come to class,

00:00:27.900 --> 00:00:29.250
they're doing problem solving.

00:00:29.250 --> 00:00:32.310
And they have the teacher
there to help them out,

00:00:32.310 --> 00:00:33.040
to tutor them.

00:00:33.040 --> 00:00:34.290
And they have their peers too.

00:00:34.290 --> 00:00:35.915
And the classes a
lot of us grew up in,

00:00:35.915 --> 00:00:38.164
if you wanted to help your
peer, you'd get in trouble.

00:00:38.164 --> 00:00:39.619
You know, shh, be quiet, listen.

00:00:39.619 --> 00:00:40.660
But now it's like no, no.

00:00:40.660 --> 00:00:43.140
This is what it's all about--
getting help from your peers,

00:00:43.140 --> 00:00:45.070
doing problem solving,
doing open-ended projects,

00:00:45.070 --> 00:00:46.340
interacting with your teacher.

00:00:46.340 --> 00:00:48.350
FEMALE SPEAKER 1: What do you
think your average-- maybe

00:00:48.350 --> 00:00:49.558
that's not the way to put it.

00:00:49.558 --> 00:00:51.720
How do you think a lot
of classes are failing?

00:00:51.720 --> 00:00:54.510
I mean, what's wrong with
the American education

00:00:54.510 --> 00:00:56.590
system in a typical
classroom, where it really

00:00:56.590 --> 00:00:57.840
isn't serving a student today?

00:00:57.840 --> 00:00:59.298
SALMAN KHAN: Yeah,
and then this is

00:00:59.298 --> 00:01:01.780
something I go into a lot
of detail on in the book.

00:01:01.780 --> 00:01:04.117
All of the paranoia
about our school system,

00:01:04.117 --> 00:01:05.700
we come look at the
national rankings,

00:01:05.700 --> 00:01:07.199
we're like, oh,
we're behind Estonia

00:01:07.199 --> 00:01:08.300
in factoring polynomials.

00:01:08.300 --> 00:01:09.383
It's the end of the world.

00:01:09.383 --> 00:01:10.870
America's going to
lose everything.

00:01:10.870 --> 00:01:11.380
And one thing--

00:01:11.380 --> 00:01:12.770
FEMALE SPEAKER 1: We're kind
of low on science and math.

00:01:12.770 --> 00:01:13.800
SALMAN KHAN: Low on
science and math.

00:01:13.800 --> 00:01:15.980
And we shouldn't get
complacent about that.

00:01:15.980 --> 00:01:19.507
But one thing I point out is if
you look at the last 50 years,

00:01:19.507 --> 00:01:21.340
and you look at the
innovation in the world,

00:01:21.340 --> 00:01:23.048
it's only been that
getting more and more

00:01:23.048 --> 00:01:24.134
concentrated in the US.

00:01:24.134 --> 00:01:26.050
If you look at the most
innovative companies--

00:01:26.050 --> 00:01:27.799
the Facebooks, the
Googles, the Twitters--

00:01:27.799 --> 00:01:29.815
they're all coming from America.

00:01:29.815 --> 00:01:32.190
And part of is because we're
the most creative countries.

00:01:32.190 --> 00:01:33.850
It's innovative.

00:01:33.850 --> 00:01:35.640
Failure isn't stigmatized.

00:01:35.640 --> 00:01:38.059
And so instead of this model
of education that we have,

00:01:38.059 --> 00:01:39.850
where all the students
are batched together

00:01:39.850 --> 00:01:42.710
and there are passive lecturers,
and they're pushed forward?

00:01:42.710 --> 00:01:45.330
This is a model inherited
from Prussia, a country that

00:01:45.330 --> 00:01:48.410
does not exist
anymore, 200 years ago.

00:01:48.410 --> 00:01:50.260
And so what I point
out instead of trying

00:01:50.260 --> 00:01:52.926
to compare our Prussian model to
the Prussian model in Singapore

00:01:52.926 --> 00:01:55.060
and the Prussian model
in Finland, all of which

00:01:55.060 --> 00:01:58.190
are passive models, we should
make our model more American.

00:01:58.190 --> 00:02:00.440
Make it interactive when
people come to the classroom.

00:02:00.440 --> 00:02:01.910
Give room for creativity.

00:02:01.910 --> 00:02:04.790
If you get a C or a D,
it's not about failure.

00:02:04.790 --> 00:02:06.676
It's about, well,
make it better then.

00:02:06.676 --> 00:02:09.090
MALE SPEAKER: I find this
fascinating in the context

00:02:09.090 --> 00:02:12.570
of something else, which is like
the idea of stereotyped threat.

00:02:12.570 --> 00:02:15.410
And this is this idea that
sometimes in classrooms,

00:02:15.410 --> 00:02:19.190
some kids feel like there's a
threat response that they will

00:02:19.190 --> 00:02:21.170
be stereotyped if
they ask questions

00:02:21.170 --> 00:02:23.940
when they don't
understand something.

00:02:23.940 --> 00:02:26.560
So the idea that
you could go back

00:02:26.560 --> 00:02:29.150
and-- you don't understand that
you could listen to it again

00:02:29.150 --> 00:02:32.400
on your own and then
seek help at another time

00:02:32.400 --> 00:02:33.660
or in your own pace.

00:02:33.660 --> 00:02:36.860
So girls sometimes
feel this threat

00:02:36.860 --> 00:02:38.566
when they're in math classes.

00:02:38.566 --> 00:02:39.940
They found that
African Americans

00:02:39.940 --> 00:02:43.077
feel this threat a lot of
times in classes in general,

00:02:43.077 --> 00:02:44.910
that they feel like
they're asking questions

00:02:44.910 --> 00:02:47.140
that they shouldn't be asking.

00:02:47.140 --> 00:02:49.780
And therefore, they don't do it.

00:02:49.780 --> 00:02:52.824
And this seems like it gets
around that whole concept.

00:02:52.824 --> 00:02:53.740
Am I right about that?

00:02:53.740 --> 00:02:54.573
SALMAN KHAN: No, no.

00:02:54.573 --> 00:02:56.323
You're hitting, I
think, the core problem.

00:02:56.323 --> 00:02:58.697
When people say, oh, but in
lecture, I can ask questions.

00:02:58.697 --> 00:02:59.430
I was like, no.

00:02:59.430 --> 00:03:01.874
Three people have the
guts to ask a question.

00:03:01.874 --> 00:03:04.040
And if you're in an algebra
class and you forgot how

00:03:04.040 --> 00:03:06.030
to multiply decimals,
or you forgot--

00:03:06.030 --> 00:03:07.810
you don't even know your, maybe
you don't-- and we've see this

00:03:07.810 --> 00:03:09.270
is in some algebra classes.

00:03:09.270 --> 00:03:10.690
There's no way you're going to
raise your hand and say, wait,

00:03:10.690 --> 00:03:11.890
I forgot my fourth grade math.

00:03:11.890 --> 00:03:12.122
FEMALE SPEAKER 2: OK.

00:03:12.122 --> 00:03:13.872
You've taught more
classes on Khan Academy

00:03:13.872 --> 00:03:17.080
than Harvard University has
offered since its founding.

00:03:17.080 --> 00:03:20.420
What is your vision for
future of education globally?

00:03:20.420 --> 00:03:22.700
SALMAN KHAN: We want
to keep growing, get

00:03:22.700 --> 00:03:24.200
to hundreds of
millions of students.

00:03:24.200 --> 00:03:26.340
We've translated our
content into 12 languages.

00:03:26.340 --> 00:03:28.130
It's being used
around the world.

00:03:28.130 --> 00:03:30.037
We want to become
more interactive.

00:03:30.037 --> 00:03:31.870
And we hope that the
conversation isn't just

00:03:31.870 --> 00:03:34.740
about-- a lot of the,
within this Prussian model,

00:03:34.740 --> 00:03:36.270
how do we tweak the system?

00:03:36.270 --> 00:03:37.364
But it's about time.

00:03:37.364 --> 00:03:39.030
It's been 200 years,
and we can actually

00:03:39.030 --> 00:03:40.410
fundamentally rethink the model.

00:03:40.410 --> 00:03:42.350
So it's not this passive system.

00:03:42.350 --> 00:03:44.050
It's much more.


Sal Khan on Piers Morgan Tonight (Oct 5, 2012)

WEBVTT
Kind: captions
Language: en

00:00:02.617 --> 00:00:04.200
PIERS MORGAN: With
other countries now

00:00:04.200 --> 00:00:07.420
steaming past America, what
is the number one thing

00:00:07.420 --> 00:00:11.544
you want to see whoever wins
the next election do about this?

00:00:11.544 --> 00:00:12.960
SALMAN KHAN: I
think there's going

00:00:12.960 --> 00:00:16.359
to be a broad push to making
classrooms more human.

00:00:16.359 --> 00:00:18.025
And when you have 42
people or 30 people

00:00:18.025 --> 00:00:21.930
or even 20 people in a room
and it's all about a lecture,

00:00:21.930 --> 00:00:23.950
no matter how good you
get that ratio down,

00:00:23.950 --> 00:00:25.600
it's still a passive experience.

00:00:25.600 --> 00:00:26.850
It's what we all went through.

00:00:26.850 --> 00:00:29.500
You're looking at a clock,
waiting for the period to end.

00:00:29.500 --> 00:00:30.990
And so what we're
talking about is

00:00:30.990 --> 00:00:33.260
technology not to replace what's
happening in the classroom,

00:00:33.260 --> 00:00:34.330
but to make the
classroom better.

00:00:34.330 --> 00:00:36.000
If lectures can happen
at a student's own pace,

00:00:36.000 --> 00:00:37.800
if a lot of the problem
solving can happen,

00:00:37.800 --> 00:00:39.508
can we use the class
time for interaction

00:00:39.508 --> 00:00:42.200
between the peers, interaction
between the teacher?

00:00:42.200 --> 00:00:44.410
So even if you have the
unfortunate situation

00:00:44.410 --> 00:00:47.200
of 42 students, at least let
them interact with each other.

00:00:47.200 --> 00:00:48.562
And let them teach each other.

00:00:48.562 --> 00:00:50.770
Let them have more opportunities
to actually interact

00:00:50.770 --> 00:00:51.810
with the teacher.

00:00:51.810 --> 00:00:54.150
PIERS MORGAN: But
is the right move

00:00:54.150 --> 00:00:56.940
forward for kids to be
doing as much work at home

00:00:56.940 --> 00:00:58.930
as they do at
school, and doing it

00:00:58.930 --> 00:01:02.950
on computers, which is their
natural habitat, anyway?

00:01:02.950 --> 00:01:03.620
SALMAN KHAN: No.

00:01:03.620 --> 00:01:05.370
I think actually one
of the big problems--

00:01:05.370 --> 00:01:07.320
and I talk a lot
about this-- is we

00:01:07.320 --> 00:01:09.270
have this culture
of homework that

00:01:09.270 --> 00:01:11.240
creates this illusion of rigor.

00:01:11.240 --> 00:01:12.460
Oh, we're not good enough?

00:01:12.460 --> 00:01:15.100
The Estonians are beating
us at factoring polynomials?

00:01:15.100 --> 00:01:16.210
More homework.

00:01:16.210 --> 00:01:18.690
And all the studies
actually point to, well,

00:01:18.690 --> 00:01:21.140
the single biggest
determinants of student success

00:01:21.140 --> 00:01:24.370
are dinner with their
parents and sleeping.

00:01:24.370 --> 00:01:27.810
And homework, if
it's too much of it,

00:01:27.810 --> 00:01:30.240
directly goes against
both of those things.

00:01:30.240 --> 00:01:32.340
And so we've been working
with a lot of schools.

00:01:32.340 --> 00:01:33.840
What we're seeing
is if you actually

00:01:33.840 --> 00:01:35.484
allow more engagement
in the classroom,

00:01:35.484 --> 00:01:37.400
you allow students to
learn at their own pace,

00:01:37.400 --> 00:01:39.430
they actually learn
much, much more.


How many bags of potato chips do people eat?

WEBVTT
Kind: captions
Language: en

00:00:00.850 --> 00:00:03.590
Everyone in the kingdom is very
impressed with your ability

00:00:03.590 --> 00:00:06.380
to help with the party
planning, everyone

00:00:06.380 --> 00:00:09.330
except for this gentlemen
right over here.

00:00:09.330 --> 00:00:11.140
This is Arbegla.

00:00:11.140 --> 00:00:13.840
And he is the
king's top adviser,

00:00:13.840 --> 00:00:15.890
and also chief party planner.

00:00:15.890 --> 00:00:18.010
And he seems somewhat
threatened by your ability

00:00:18.010 --> 00:00:20.752
to solve these otherwise
unsolvable problems,

00:00:20.752 --> 00:00:22.210
or at least from
his point of view,

00:00:22.210 --> 00:00:24.740
because he keeps over-ordering
or under-ordering things

00:00:24.740 --> 00:00:26.110
like cupcakes.

00:00:26.110 --> 00:00:30.150
And he says, king, that
cupcake problem was easy.

00:00:30.150 --> 00:00:32.870
Ask them about the
potato chip issue,

00:00:32.870 --> 00:00:35.330
because we could never get
the potato chips right.

00:00:35.330 --> 00:00:37.820
And so the king says,
Arbegla, that's a good idea.

00:00:37.820 --> 00:00:39.520
We need to get the
potato chips right.

00:00:39.520 --> 00:00:41.420
So he comes to you
and says, how do we

00:00:41.420 --> 00:00:44.119
figure out, on average, how many
potato chips we need to order?

00:00:44.119 --> 00:00:45.660
And to do that, we
have to figure out

00:00:45.660 --> 00:00:47.910
how much, on average,
does each man eat

00:00:47.910 --> 00:00:49.670
and how much each woman eats.

00:00:49.670 --> 00:00:51.606
You say, well, what
about the children?

00:00:51.606 --> 00:00:52.980
The king says, in
our kingdom, we

00:00:52.980 --> 00:00:55.560
forbid potato
chips for children.

00:00:55.560 --> 00:00:58.400
You say, oh, well,
that's all and good.

00:00:58.400 --> 00:01:01.070
Tell me what happened
at the previous parties.

00:01:01.070 --> 00:01:03.940
And so the king says, you might
remember, at the last party,

00:01:03.940 --> 00:01:06.420
in fact, the last two
parties, we had 500 adults.

00:01:06.420 --> 00:01:11.725
At the last party, 200 of
them were men, and 300 of them

00:01:11.725 --> 00:01:12.225
were women.

00:01:15.070 --> 00:01:21.860
And in total, they ate
1,200 bags of potato chips.

00:01:21.860 --> 00:01:23.810
And you say, what about
the party before that?

00:01:23.810 --> 00:01:26.140
He says, that one, we had a
bigger skew towards women.

00:01:26.140 --> 00:01:31.190
We only had 100 men,
and we have 400 women.

00:01:33.700 --> 00:01:35.870
And that time, we
actually had fewer bags

00:01:35.870 --> 00:01:42.130
consumed-- 1,100
bags of potato chips.

00:01:42.130 --> 00:01:44.830
So you say, OK, king
and Arbegla, this

00:01:44.830 --> 00:01:47.020
seems like a fairly
straightforward thing.

00:01:47.020 --> 00:01:50.300
Let me define some variables
to represent our unknowns.

00:01:50.300 --> 00:01:51.830
So you go ahead
and you say, well,

00:01:51.830 --> 00:02:06.559
let's let m equal the number
of bags eaten by each man.

00:02:06.559 --> 00:02:08.100
And you could think
of it on average,

00:02:08.100 --> 00:02:09.878
or maybe all the
men in that kingdom

00:02:09.878 --> 00:02:10.919
are completely identical.

00:02:10.919 --> 00:02:14.410
Or maybe it's the average number
of bags eaten by each man.

00:02:14.410 --> 00:02:25.620
And let's let w equal the number
of bags eaten by each woman.

00:02:25.620 --> 00:02:28.960
And so with these
definitions of our variables,

00:02:28.960 --> 00:02:31.720
let's think about
how we can represent

00:02:31.720 --> 00:02:34.810
this first piece of information,
this piece of information

00:02:34.810 --> 00:02:36.940
in green.

00:02:36.940 --> 00:02:39.210
Well, let's think about
the total number of bags

00:02:39.210 --> 00:02:41.600
that the men ate.

00:02:41.600 --> 00:02:44.020
You had 200 men.

00:02:44.020 --> 00:02:45.390
Let me scroll over a little bit.

00:02:45.390 --> 00:02:50.750
You had 200 men, and they each
ate m bags, m bags per man.

00:02:50.750 --> 00:02:52.715
So the men at this
first party collectively

00:02:52.715 --> 00:02:55.150
ate 200 times m bags.

00:02:55.150 --> 00:02:58.640
If m is 10 bags per man,
then this would be 2,000.

00:02:58.640 --> 00:03:02.110
If m was 5 bags per man,
then this would be 5,000.

00:03:02.110 --> 00:03:04.610
We don't know what m
is, but 200 times m

00:03:04.610 --> 00:03:06.500
is the total eaten by the men.

00:03:06.500 --> 00:03:08.560
Same logic-- total
eaten by the women

00:03:08.560 --> 00:03:14.570
is 300 women times the number
of bags eaten by each woman.

00:03:14.570 --> 00:03:17.160
And so if you add the total to
eaten by the men and the women,

00:03:17.160 --> 00:03:22.200
you get the 1,200 bags.

00:03:22.200 --> 00:03:25.440
So this is information,
written algebraically,

00:03:25.440 --> 00:03:28.150
given these variable
definitions.

00:03:28.150 --> 00:03:30.812
Now, let's do the same
thing with the second part

00:03:30.812 --> 00:03:33.020
of the information that they
gave us right over here.

00:03:33.020 --> 00:03:35.436
Let's think about how we can
represent this algebraically.

00:03:37.850 --> 00:03:40.160
Well, similar logic--
what was a total

00:03:40.160 --> 00:03:42.070
that the men ate at that party?

00:03:42.070 --> 00:03:45.850
It was 100 men times
m bags per man.

00:03:45.850 --> 00:03:48.710
And we're assuming that m
is the same across parties,

00:03:48.710 --> 00:03:52.330
that men, on average, always
eat the same number of bags.

00:03:52.330 --> 00:03:54.820
And how many did the women
eat at that second party?

00:03:54.820 --> 00:03:56.460
Well, you had 400 women.

00:03:56.460 --> 00:04:00.140
And on average, they
ate w bags per woman.

00:04:00.140 --> 00:04:02.550
So this is 400 times
w is the total number

00:04:02.550 --> 00:04:03.620
that the women ate.

00:04:03.620 --> 00:04:05.850
You add those two together,
you get the total number

00:04:05.850 --> 00:04:07.150
that all the adults ate.

00:04:07.150 --> 00:04:11.680
So this is going
to be 1,100 bags.

00:04:11.680 --> 00:04:13.530
So it looks pretty similar now.

00:04:13.530 --> 00:04:17.190
You have a system of two
equations with two unknowns.

00:04:17.190 --> 00:04:21.430
And so you try your
best to solve it.

00:04:21.430 --> 00:04:23.680
But when you solve it, you
see something interesting.

00:04:23.680 --> 00:04:25.100
Last time, it was
very convenient.

00:04:25.100 --> 00:04:28.950
You had a, I think it was
a 500 here, for 500 adults,

00:04:28.950 --> 00:04:30.170
and you had another 500.

00:04:30.170 --> 00:04:31.650
And so it seemed
like it was pretty

00:04:31.650 --> 00:04:33.750
easy to cancel out
one of the variables.

00:04:33.750 --> 00:04:36.070
Here it seems a little
bit more difficult.

00:04:36.070 --> 00:04:38.660
What's multiplying by the
m's, it's different here.

00:04:38.660 --> 00:04:41.290
The coefficient on the w
is different over here.

00:04:41.290 --> 00:04:44.210
You say, well, maybe I can
change one of these equations

00:04:44.210 --> 00:04:46.670
so it makes it a little
bit easier to cancel out

00:04:46.670 --> 00:04:48.470
with the other equation.

00:04:48.470 --> 00:04:55.050
So what if, for example, I
were to take this blue equation

00:04:55.050 --> 00:04:58.760
right over here and
multiply it by negative 2?

00:04:58.760 --> 00:05:00.620
And you might say,
well, Sal, why are we

00:05:00.620 --> 00:05:01.870
multiplying it by negative 2?

00:05:01.870 --> 00:05:03.960
Well, if were to multiply
it by negative 2,

00:05:03.960 --> 00:05:07.790
this 100m would become
a negative 200m.

00:05:07.790 --> 00:05:10.190
And if it was a
negative 200m, then

00:05:10.190 --> 00:05:12.710
that would cancel out
with a positive 200m

00:05:12.710 --> 00:05:14.010
when we add the two.

00:05:14.010 --> 00:05:15.180
So let's see what happens.

00:05:15.180 --> 00:05:19.920
So let's multiply this blue
equation by negative 2.

00:05:19.920 --> 00:05:22.000
We're going to
multiply by negative 2.

00:05:22.000 --> 00:05:23.870
Let me scroll over to
the left a little bit.

00:05:23.870 --> 00:05:24.536
So what happens?

00:05:24.536 --> 00:05:27.630
Remember, when we
multiply an equation,

00:05:27.630 --> 00:05:29.380
we can't just do one
side of the equation.

00:05:29.380 --> 00:05:31.129
We have to do the
entire equation in order

00:05:31.129 --> 00:05:33.060
for the equality to hold true.

00:05:33.060 --> 00:05:38.060
So negative 2 times
100m is negative 200m.

00:05:38.060 --> 00:05:41.660
Negative 2 times 400w-- there's
a positive right over there.

00:05:41.660 --> 00:05:44.810
So it becomes negative 800w.

00:05:44.810 --> 00:05:47.370
And then negative 2-- now,
we did the left hand side,

00:05:47.370 --> 00:05:49.360
but we also have to do
the right hand side.

00:05:49.360 --> 00:05:55.120
Negative 2 times 1,100
is negative 2,200.

00:05:55.120 --> 00:05:56.895
So just to be
clear, this equation

00:05:56.895 --> 00:05:58.470
that I just wrote
here essentially

00:05:58.470 --> 00:06:00.680
has the same information
we just manipulated.

00:06:00.680 --> 00:06:03.400
We just changed this equation,
multiplied both sides

00:06:03.400 --> 00:06:04.410
by negative 2.

00:06:04.410 --> 00:06:06.672
But it's kind of
the same constraint.

00:06:06.672 --> 00:06:08.130
But what makes this
interesting is,

00:06:08.130 --> 00:06:10.690
now, we can rewrite
this green equation.

00:06:10.690 --> 00:06:13.200
Let me do it over
here, this first one.

00:06:13.200 --> 00:06:20.835
200m plus 300w is
equal to 1,200.

00:06:20.835 --> 00:06:22.960
And the whole reason why
I multiplied by negative 2

00:06:22.960 --> 00:06:25.090
is, so that if I were
to add these two things,

00:06:25.090 --> 00:06:27.810
I might be able to get rid
of that variable over there.

00:06:27.810 --> 00:06:28.862
And so let's do that.

00:06:28.862 --> 00:06:31.320
Let's add the left hand sides,
and let's add the right hand

00:06:31.320 --> 00:06:31.880
sides.

00:06:31.880 --> 00:06:33.588
And you could literally
view it as, we're

00:06:33.588 --> 00:06:35.360
starting with this
blue equation.

00:06:35.360 --> 00:06:37.970
We're adding this
quantity, the left hand

00:06:37.970 --> 00:06:40.770
side of the yellow equation to
the left hand side of the blue.

00:06:40.770 --> 00:06:42.632
And then 1,200 is
the exact same thing

00:06:42.632 --> 00:06:44.340
that we're adding to
the right hand side.

00:06:44.340 --> 00:06:46.270
We know that this
is equal to this.

00:06:46.270 --> 00:06:48.740
So we can add this to the
left hand side and this

00:06:48.740 --> 00:06:50.170
to the right hand side.

00:06:50.170 --> 00:06:51.592
So let's see what happens.

00:06:51.592 --> 00:06:53.300
So the good thing is,
the whole reason we

00:06:53.300 --> 00:06:55.300
multiplied it by negative
2, so that these two

00:06:55.300 --> 00:06:56.336
characters cancel out.

00:06:56.336 --> 00:06:57.460
You add those two together.

00:06:57.460 --> 00:06:59.870
You just get 0m or just 0.

00:06:59.870 --> 00:07:03.990
You have negative
800w plus 300w.

00:07:03.990 --> 00:07:06.881
Well, that's negative 500w.

00:07:06.881 --> 00:07:08.380
And then on the
right hand side, you

00:07:08.380 --> 00:07:11.140
have negative 2,200 plus 1,200.

00:07:11.140 --> 00:07:14.544
So that's negative 1,000.

00:07:14.544 --> 00:07:16.210
And now this is pretty
straightforward--

00:07:16.210 --> 00:07:18.460
one equation, one unknown,
a fairly straightforward

00:07:18.460 --> 00:07:19.230
equation.

00:07:19.230 --> 00:07:22.920
We divide both sides by
the coefficient of w,

00:07:22.920 --> 00:07:23.930
multiplying w.

00:07:23.930 --> 00:07:28.570
So divide by negative 500 on
the left, divide by negative 500

00:07:28.570 --> 00:07:29.500
on the right.

00:07:29.500 --> 00:07:34.750
And we are left with
w is equal to 2.

00:07:34.750 --> 00:07:38.440
On average, women ate
two bags of potato chips

00:07:38.440 --> 00:07:39.270
at these parties.

00:07:39.270 --> 00:07:42.080
We're assuming that's
constant across the parties.

00:07:42.080 --> 00:07:44.280
So let's think about how
you would then figure out

00:07:44.280 --> 00:07:48.810
how many bags, on
average, each man ate.

00:07:48.810 --> 00:07:51.026
Well, to do that,
we just go back

00:07:51.026 --> 00:07:52.400
to either one of
these equations.

00:07:52.400 --> 00:07:55.850
In the last set of videos, I
went to the first equation.

00:07:55.850 --> 00:07:58.200
I'll show that the second
equation should also work.

00:07:58.200 --> 00:07:59.660
Either one should work.

00:07:59.660 --> 00:08:01.765
So let's substitute back
into the second equation.

00:08:01.765 --> 00:08:04.140
And you could either pick this
version of it or this one.

00:08:04.140 --> 00:08:05.850
But I'll pick the original one.

00:08:05.850 --> 00:08:09.190
So you have 100
times m, which we're

00:08:09.190 --> 00:08:12.400
trying to figure out,
plus 400 times-- well,

00:08:12.400 --> 00:08:16.010
we now know that w is
equal to 2-- 400 times

00:08:16.010 --> 00:08:21.610
2 is equal to 1,100.

00:08:21.610 --> 00:08:28.950
So you have 100m plus
800 is equal to 1,100.

00:08:28.950 --> 00:08:32.000
And now, to solve for
m, we could subtract 800

00:08:32.000 --> 00:08:32.685
from both sides.

00:08:36.650 --> 00:08:43.890
And we are left with
100m is equal to 300.

00:08:43.890 --> 00:08:49.690
And now, divide
both sides by 100.

00:08:49.690 --> 00:08:53.490
And we are left with m, which
is, on average, the number

00:08:53.490 --> 00:08:57.940
of bags of chips each
man eats is equal to 3.

00:08:57.940 --> 00:09:00.490
So you have solved
Arbegla's problem,

00:09:00.490 --> 00:09:03.220
what he thought was a
difficult problem, using

00:09:03.220 --> 00:09:06.000
the magical, mystical
powers of algebra.

00:09:06.000 --> 00:09:09.780
You were able to tell the king
in his party planning process

00:09:09.780 --> 00:09:12.080
that, on average,
the men will eat

00:09:12.080 --> 00:09:14.860
three bags of potato chips each.

00:09:14.860 --> 00:09:16.930
And on average,
the women will eat

00:09:16.930 --> 00:09:20.510
two bags of potato chips each.


King's cupcakes: Solving systems by elimination

WEBVTT
Kind: captions
Language: en

00:00:00.630 --> 00:00:05.100
After you cross the troll's
bridge and you save the prince

00:00:05.100 --> 00:00:10.060
or princess, you return them
back to their father, the King.

00:00:10.060 --> 00:00:13.330
And he's so excited that you
returned their son or daughter

00:00:13.330 --> 00:00:17.430
to him that he wants to
throw a brunch in your honor.

00:00:17.430 --> 00:00:19.430
But he has a little
bit of a conundrum

00:00:19.430 --> 00:00:20.960
in throwing the brunch.

00:00:20.960 --> 00:00:27.731
He wants to figure out how
many cupcakes should he order?

00:00:27.731 --> 00:00:29.230
He doesn't want to
waste any, but he

00:00:29.230 --> 00:00:31.511
wants to make sure that
everyone has enough to eat.

00:00:31.511 --> 00:00:33.260
And you say, well
what's the problem here?

00:00:33.260 --> 00:00:35.509
And he says, well I know
adults eat a different number

00:00:35.509 --> 00:00:37.066
of cupcakes than children eat.

00:00:37.066 --> 00:00:39.190
And I know that in my
kingdom, an adult will always

00:00:39.190 --> 00:00:41.290
eat the same amount
and a child will always

00:00:41.290 --> 00:00:42.690
eat the same amount.

00:00:42.690 --> 00:00:45.255
And so you say, King, well what
information can you give me?

00:00:45.255 --> 00:00:47.130
I might be able to help
you out a little bit.

00:00:47.130 --> 00:00:50.110
You're feeling very confident
after this troll situation.

00:00:50.110 --> 00:00:57.680
And he says, well I know at the
last party we had 500 adults

00:00:57.680 --> 00:01:04.420
and we had 200
children, and combined

00:01:04.420 --> 00:01:10.220
they ate 2,900 cupcakes.

00:01:10.220 --> 00:01:11.944
And you say, OK,
that's interesting.

00:01:11.944 --> 00:01:14.110
But I think I'll need a
little bit more information.

00:01:14.110 --> 00:01:15.160
Have you thrown
parties before then?

00:01:15.160 --> 00:01:16.250
And the king says,
of course I have.

00:01:16.250 --> 00:01:17.257
I like to throw parties.

00:01:17.257 --> 00:01:19.090
Well what happened at
the party before that?

00:01:19.090 --> 00:01:24.840
And he says, well there
we also had 500 adults

00:01:24.840 --> 00:01:26.660
and we had 300 children.

00:01:29.002 --> 00:01:30.460
And you say, well
how many cupcakes

00:01:30.460 --> 00:01:31.501
were eaten at that party?

00:01:31.501 --> 00:01:37.200
And he says, well we know
it was 3,100 cupcakes.

00:01:37.200 --> 00:01:38.750
And so you get a
tingling feeling

00:01:38.750 --> 00:01:41.552
that a little bit of algebra
might apply over here.

00:01:41.552 --> 00:01:42.760
And you say, well let me see.

00:01:42.760 --> 00:01:44.010
What do we need to figure out?

00:01:44.010 --> 00:01:46.720
We need to figure out the
number of cupcakes on average

00:01:46.720 --> 00:01:48.260
that an adult will eat.

00:01:48.260 --> 00:01:56.750
So number of cupcakes
for an adult.

00:01:56.750 --> 00:02:00.220
And we also need to
figure out the number

00:02:00.220 --> 00:02:03.760
of cupcakes for a child.

00:02:03.760 --> 00:02:06.464
So these are the
two things that we

00:02:06.464 --> 00:02:07.880
need to figure out
because then we

00:02:07.880 --> 00:02:09.880
can know how many adults
and children are coming

00:02:09.880 --> 00:02:12.210
to the next branch that are
being held in your honor

00:02:12.210 --> 00:02:14.310
and get the exact right
number of cupcakes.

00:02:14.310 --> 00:02:16.310
So those are things you're
trying to figure out.

00:02:16.310 --> 00:02:18.360
And we don't know
what those things are.

00:02:18.360 --> 00:02:23.720
Let's define some variables
that represent those things.

00:02:23.720 --> 00:02:25.160
Well let's do a for adults.

00:02:25.160 --> 00:02:27.170
Let's let a equal the
number of cupcakes

00:02:27.170 --> 00:02:29.370
that, on average,
each adult eats.

00:02:29.370 --> 00:02:31.010
And let's do c for children.

00:02:31.010 --> 00:02:35.700
So c is the number of cupcakes
for a child on average.

00:02:35.700 --> 00:02:38.060
So given that
information, let's see

00:02:38.060 --> 00:02:41.810
how we can represent what the
King has told us algebraically.

00:02:41.810 --> 00:02:44.620
So let's think about this
orange information first.

00:02:44.620 --> 00:02:47.626
How could we represent
this algebraically?

00:02:47.626 --> 00:02:49.580
Well let's think about
how many cupcakes

00:02:49.580 --> 00:02:51.470
the adults ate at that party.

00:02:51.470 --> 00:02:54.670
You had 500 adults, and
on average, each of them

00:02:54.670 --> 00:02:56.520
exactly a cupcakes.

00:02:56.520 --> 00:02:58.730
So the total number of
cupcakes that the adults ate

00:02:58.730 --> 00:03:01.170
were 500 times a.

00:03:01.170 --> 00:03:02.420
How many did the children eat?

00:03:02.420 --> 00:03:03.460
Well same logic.

00:03:03.460 --> 00:03:08.360
You had 200 children and
they each ate c cupcakes.

00:03:08.360 --> 00:03:11.180
So 200 times c is the
total number of cupcakes

00:03:11.180 --> 00:03:12.320
that the children ate.

00:03:12.320 --> 00:03:13.500
Well how much did
they eat in total?

00:03:13.500 --> 00:03:15.249
Well it's the total
number that the adults

00:03:15.249 --> 00:03:17.370
ate plus the total number
that the children ate

00:03:17.370 --> 00:03:21.830
which is 2,900 cupcakes.

00:03:21.830 --> 00:03:24.830
So let's do that and apply that
same logic to the blue party

00:03:24.830 --> 00:03:26.760
right over here, this
blue information.

00:03:26.760 --> 00:03:30.690
How can we represent
this algebraically?

00:03:30.690 --> 00:03:33.410
Well once again, how many total
cupcakes did the adults eat?

00:03:33.410 --> 00:03:36.656
Well, you had 500
adults and they each

00:03:36.656 --> 00:03:40.115
ate a cupcakes, which
is an unknown right now.

00:03:40.115 --> 00:03:41.490
And then what
about the children?

00:03:41.490 --> 00:03:45.639
Well you had 300 children
and they each ate c cupcakes.

00:03:45.639 --> 00:03:47.180
And so if you add
up all the cupcakes

00:03:47.180 --> 00:03:50.670
that the adults ate plus all the
cupcakes that the children ate,

00:03:50.670 --> 00:03:53.984
you get to 3,100 cupcakes.

00:03:53.984 --> 00:03:55.650
So this is starting
to look interesting.

00:03:55.650 --> 00:03:56.910
I have two equations.

00:03:56.910 --> 00:04:00.360
I have a system of two
equations with two unknowns.

00:04:00.360 --> 00:04:02.570
And you know from your
experience with the troll

00:04:02.570 --> 00:04:04.440
that you should be
able to solve this.

00:04:04.440 --> 00:04:07.105
You could solve it graphically
like you did in the past,

00:04:07.105 --> 00:04:08.480
but now you feel
that there could

00:04:08.480 --> 00:04:10.480
be another tool in your
tool kit which is really

00:04:10.480 --> 00:04:13.850
just an application of the
algebra that you already know.

00:04:13.850 --> 00:04:17.440
So think a little bit about
how you might do this.

00:04:17.440 --> 00:04:19.800
So let's rewrite this first
equation right over here.

00:04:19.800 --> 00:04:30.110
So we have 500a plus 200c
is equal to 2,900 cupcakes.

00:04:30.110 --> 00:04:33.720
Now, it would be good if we
could get rid of this 500a

00:04:33.720 --> 00:04:34.530
somehow.

00:04:34.530 --> 00:04:38.090
Well you might say, well
let me just subtract 500a.

00:04:38.090 --> 00:04:41.770
So you might say, oh, I
just want to subtract 500a.

00:04:41.770 --> 00:04:44.040
But if you subtracted 500a
from the left hand side,

00:04:44.040 --> 00:04:46.519
you'd also have to subtract
500a from the right hand side.

00:04:46.519 --> 00:04:48.060
And so the a wouldn't
just disappear.

00:04:48.060 --> 00:04:49.950
It would just end up
on the right hand side,

00:04:49.950 --> 00:04:51.640
and you would still
have one equation

00:04:51.640 --> 00:04:54.190
with two unknowns which
isn't too helpful.

00:04:54.190 --> 00:04:55.720
But you see something
interesting.

00:04:55.720 --> 00:04:57.720
You're like, well
this is a 500a here.

00:04:57.720 --> 00:05:01.340
What if I subtracted
a 500a and this 300c?

00:05:01.340 --> 00:05:05.770
So if I subtracted
the 500a and the 300c

00:05:05.770 --> 00:05:06.880
from the left hand side.

00:05:06.880 --> 00:05:08.030
And you're like, well
why is that useful?

00:05:08.030 --> 00:05:09.890
You're going to do the same
thing on the right hand side

00:05:09.890 --> 00:05:12.550
and then you're going to have
an a and a c on the right hand.

00:05:12.550 --> 00:05:15.207
And you just say, hold on,
hold on one second here.

00:05:15.207 --> 00:05:17.040
Hold on, I guess you're
talking to yourself.

00:05:17.040 --> 00:05:18.640
Hold on one second.

00:05:18.640 --> 00:05:21.630
I'm subtracting the left
hand side of this equation,

00:05:21.630 --> 00:05:23.640
but this left hand side
is the exact same thing

00:05:23.640 --> 00:05:25.040
as this right hand side.

00:05:25.040 --> 00:05:28.050
So here I could
subtract 500a and 300c,

00:05:28.050 --> 00:05:33.140
and I could do 500a and
subtract 300c over here.

00:05:33.140 --> 00:05:35.570
But we know that
subtracting 500a and 300c,

00:05:35.570 --> 00:05:39.430
that's the exact same
thing as subtracting 3,100.

00:05:39.430 --> 00:05:40.690
Let me make it clear.

00:05:40.690 --> 00:05:47.060
This is 500a minus 300c
is the exact same thing

00:05:47.060 --> 00:05:52.260
as subtracting 500a plus 300c.

00:05:52.260 --> 00:05:56.920
And we know that 500a plus
300c is exactly 3,100.

00:05:56.920 --> 00:05:58.040
This is 3,100.

00:05:58.040 --> 00:06:00.640
This is what the second
information gave us.

00:06:00.640 --> 00:06:04.190
So instead of subtracting
500a and minus 300c,

00:06:04.190 --> 00:06:06.770
we can just subtract 3,100.

00:06:06.770 --> 00:06:07.720
So let me do that.

00:06:07.720 --> 00:06:09.260
This is exciting.

00:06:09.260 --> 00:06:11.390
So let me clear that out.

00:06:11.390 --> 00:06:12.860
So let's clear that out.

00:06:12.860 --> 00:06:15.270
And so here, instead
of doing this,

00:06:15.270 --> 00:06:19.380
I can subtract the exact same
value, which we know is 3,100,

00:06:19.380 --> 00:06:21.172
subtract 3,100.

00:06:21.172 --> 00:06:22.630
So looking at it
this way, it looks

00:06:22.630 --> 00:06:25.150
like we're subtracting
this bottom equation

00:06:25.150 --> 00:06:27.540
from the top equation, but
we're really just subtracting

00:06:27.540 --> 00:06:29.010
the same thing from both sides.

00:06:29.010 --> 00:06:31.180
This is just very
basic algebra here.

00:06:31.180 --> 00:06:34.920
But if we do that,
let's see what happens.

00:06:34.920 --> 00:06:38.940
So on the left hand side, 500a
minus 500a, those cancel out.

00:06:38.940 --> 00:06:44.280
200c minus 300c, that
gives us negative 100c.

00:06:44.280 --> 00:06:47.640
And on the right hand
side, 2,900 minus 3,100

00:06:47.640 --> 00:06:49.720
is negative 200.

00:06:49.720 --> 00:06:51.950
Well now we have one
equation with one unknown,

00:06:51.950 --> 00:06:53.500
and we know how to solve this.

00:06:53.500 --> 00:06:59.140
We can divide both
sides by negative 100.

00:06:59.140 --> 00:07:00.320
These cancel out.

00:07:00.320 --> 00:07:03.250
And then over here, you
end up with a positive 2.

00:07:03.250 --> 00:07:06.630
So c is equal to positive 2.

00:07:06.630 --> 00:07:08.510
So we've solved one
of the unknowns,

00:07:08.510 --> 00:07:12.010
the each child on
average drinks two cups.

00:07:12.010 --> 00:07:15.210
So c is equal to 2.

00:07:15.210 --> 00:07:17.274
So how can we figure
out what a is?

00:07:17.274 --> 00:07:18.815
Well now we can take
this information

00:07:18.815 --> 00:07:22.370
and go back into either one
of these and figure out what

00:07:22.370 --> 00:07:23.960
a has to be.

00:07:23.960 --> 00:07:26.560
So let's go back into the
orange one right over here

00:07:26.560 --> 00:07:29.550
and figure out what a has to be.

00:07:29.550 --> 00:07:38.710
So we had 500a plus 200c, but
we know what c is, c is 2.

00:07:38.710 --> 00:07:46.720
So 200 times 2 is
equal to 2,900.

00:07:46.720 --> 00:07:48.390
And now we just
have to solve for a,

00:07:48.390 --> 00:07:50.560
one equation with one unknown.

00:07:50.560 --> 00:07:55.540
So we have 500a,
200 times 2 is 400,

00:07:55.540 --> 00:07:59.100
plus 400 is equal to 2,900.

00:07:59.100 --> 00:08:02.570
We can subtract 400 from
both sides of this equation.

00:08:02.570 --> 00:08:03.880
Let me do that.

00:08:03.880 --> 00:08:10.620
Subtracting 400, and we are
left with this cancels out.

00:08:10.620 --> 00:08:13.200
And on the left hand
side, we have 500a.

00:08:13.200 --> 00:08:14.280
This is very exciting.

00:08:14.280 --> 00:08:15.540
We're in the home stretch.

00:08:15.540 --> 00:08:19.950
On the right hand
side, you have 2,500.

00:08:19.950 --> 00:08:22.330
500a equals 2,500.

00:08:22.330 --> 00:08:26.750
We can divide both
sides by 500, and we

00:08:26.750 --> 00:08:30.700
are left with 2,500
divided by 500 is just 5.

00:08:30.700 --> 00:08:33.690
So you have a is equal
to 5 and you're done.

00:08:33.690 --> 00:08:35.980
You have solved the
King's conundrum.

00:08:35.980 --> 00:08:39.390
Each child on average drinks
2 cups of water-- sorry,

00:08:39.390 --> 00:08:40.200
not cups of water.

00:08:40.200 --> 00:08:41.658
I don't know where
I got that from.

00:08:41.658 --> 00:08:46.140
Each child 2 cupcakes and each
adult will eat 5 cupcakes.

00:08:46.140 --> 00:08:47.439
a is equal to 5.

00:08:47.439 --> 00:08:49.730
And so based on how many
adults and children are coming

00:08:49.730 --> 00:08:52.670
to the brunch in
your honor, you now

00:08:52.670 --> 00:08:56.470
know exactly the
number of cupcakes

00:08:56.470 --> 00:08:59.970
that the King needs to order.


Solving systems of equations graphically

WEBVTT
Kind: captions
Language: en

00:00:00.830 --> 00:00:03.310
Just in case we encounter
any more trolls who

00:00:03.310 --> 00:00:05.880
want us to figure out
what types of money

00:00:05.880 --> 00:00:09.270
they have in their pockets,
we have devised an exercise

00:00:09.270 --> 00:00:11.190
for you to practice with.

00:00:11.190 --> 00:00:15.220
And this is to solve systems
of equations visually.

00:00:15.220 --> 00:00:19.080
So they say right over here,
graph this system of equations

00:00:19.080 --> 00:00:19.790
and solve.

00:00:19.790 --> 00:00:21.850
And they give us two equations.

00:00:21.850 --> 00:00:26.500
This first one in blue, y
is equal to 7/5x minus 5,

00:00:26.500 --> 00:00:30.475
and then this one in green,
y is equal to 3/5x minus 1.

00:00:30.475 --> 00:00:32.100
So let's graph each
of these, and we'll

00:00:32.100 --> 00:00:33.560
do it in the
corresponding color.

00:00:33.560 --> 00:00:35.830
So first let's graph
this first equation.

00:00:35.830 --> 00:00:39.820
So the first thing I see is
its y-intercept is negative 5.

00:00:39.820 --> 00:00:42.790
Or another way to think about
it, when x is equal to 0,

00:00:42.790 --> 00:00:45.040
y is going to be negative 5.

00:00:45.040 --> 00:00:46.320
So let's try this out.

00:00:46.320 --> 00:00:49.470
So when x is equal
to 0, y is going

00:00:49.470 --> 00:00:51.230
to be equal to negative 5.

00:00:51.230 --> 00:00:53.160
So that makes sense.

00:00:53.160 --> 00:00:55.850
And then we see
its slope is 7/5.

00:00:55.850 --> 00:00:59.340
This was conveniently placed
in slope-intercept form for us.

00:00:59.340 --> 00:01:01.310
So it's rise over run.

00:01:01.310 --> 00:01:03.540
So for every time it moves
5 to the right it's, going

00:01:03.540 --> 00:01:05.080
to move seven up.

00:01:05.080 --> 00:01:09.420
So if it moves 1, 2,
3, 4, 5 to the right,

00:01:09.420 --> 00:01:10.610
it's going to move 7 up.

00:01:10.610 --> 00:01:15.920
1, 2, 3, 4, 5, 6, 7.

00:01:15.920 --> 00:01:18.342
So it'll get right over there.

00:01:18.342 --> 00:01:20.050
Another way you could
have done it is you

00:01:20.050 --> 00:01:21.760
could have just tested
out some values.

00:01:21.760 --> 00:01:23.676
You could have said, oh,
when x is equal to 0,

00:01:23.676 --> 00:01:25.360
y is equal to negative 5.

00:01:25.360 --> 00:01:32.540
When x is equal to 5, 7/5
times 5 is 7 minus 5 is 2.

00:01:32.540 --> 00:01:35.380
So I think we've properly
graphed this top one.

00:01:35.380 --> 00:01:38.000
Let's try this bottom
one right over here.

00:01:38.000 --> 00:01:43.970
So we have when x is equal to
0, y is equal to negative 1.

00:01:43.970 --> 00:01:47.290
So when x is equal to 0,
y is equal to negative 1.

00:01:47.290 --> 00:01:49.930
And the slope is 3/5.

00:01:49.930 --> 00:01:56.100
So if we move over 5 to the
right, we will move up 3.

00:01:56.100 --> 00:01:58.580
So we will go right
over there, and it

00:01:58.580 --> 00:02:00.760
looks like they intersect
right at that point,

00:02:00.760 --> 00:02:04.400
right at the point x is
equal to 5, y is equal to 2.

00:02:04.400 --> 00:02:10.120
So we'll type in x is equal
to 5, y is equal to 2.

00:02:10.120 --> 00:02:12.810
And you could even verify
by substituting those values

00:02:12.810 --> 00:02:14.310
into both equations,
to show that it

00:02:14.310 --> 00:02:17.250
does satisfy both constraints.

00:02:17.250 --> 00:02:19.580
So let's check our answer.

00:02:19.580 --> 00:02:20.931
And it worked.