Subjects and predicates

WEBVTT
Kind: captions
Language: en

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- [Voiceover] Hello, grammarians.

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Hello, Paige.

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- [Paige] Hi, David.

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- [David] Today we're going to talk about

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identifying subjects and predicates

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and in order to do that, we
shall begin with a sentence.

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Paige, would you read
me the sentence, please?

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- [Paige] I bought a crate of goblin hats.

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- [David] Thank you, Paige.

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So Paige, do you think
that's hats for goblins,

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or hats that make you look like a goblin?

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- [Paige] Well, I bought it, so I can say

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that it is both.

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- [David] So we could go either
way is what you're saying.

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- [Paige] (Laughs) Oh, yeah.

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- [David] A sentence is
kind of a like a car.

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It's got a lot of different
parts, like an engine,

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or wheels, or a body, whatever.

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A sentence is very much the same way

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and you can divide up
a sentence into parts.

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Today, we're going to be
dividing up the sentence

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into subject and predicate.

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Paige, what is the subject of a sentence?

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- [Paige] The subject
is a noun or a pronoun

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that is doing the action in the sentence

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or performing the verb.

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- [David] What does that
mean to perform a verb?

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- [Paige] Right, so a verb
isn't always an action, right?

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That's why I wanted to clarify.

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- [David] Mm-hmm.

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- [Paige] Because you
can say, "I am happy."

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Am is a verb, but that's not
an action that I'm doing.

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- [David] Right, you
can't just actively am.

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- [Paige] Right. (laughs)

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- [David] But in the
sentence, "I am happy,"

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the subject I is performing
the verb to be, or am.

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- [Paige] Right.

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- [David] Gotcha.

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What is a predicate?

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- [Paige] A predicate is all
of the rest of the sentence

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that isn't the subject.

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What it really is is the verb

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and all of the parts that
are related to the verb.

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Yeah, verb and its pals, that's good.

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- [David] Let's apply that
approach to goblin hat sentence.

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- [Paige] Mm-hmm.

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- [David] Okay, so I'm
looking for a noun or pronoun

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that performs a verb in the sentence.

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Well, I found the verb
and the verb is bought.

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Who's doing the buying?

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I am.

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- [Paige] Right.

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- [David] So our subject is I.

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- [Paige] Yeah.

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- [David] Then predicate is basically

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everything else, right?

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It's bought, what did I buy?

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A crate of goblin hats.

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- [Paige] Right.

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You can see that a crate of goblin hats

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is also a noun, right?

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But it's not doing
anything in the sentence.

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I am buying.

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- [David] Just because there's a noun,

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just because there's another
noun in the sentence,

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like crate or goblin hats,
doesn't necessarily mean

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that it's the subject.

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- [Paige] Right.

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- [David] So you have to
look for the thing that is

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performing the verb.

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- [Paige] Exactly.

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- [David] Paige, I think
that covers everything except

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exactly what a goblin hat is,
but we can talk about that

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some other time.

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- [Paige] Yeah.

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- [David] That's identifying
subjects and predicates.

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You can learn anything.

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David out.

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- [Paige] Paige out.


Three types of sentence

WEBVTT
Kind: captions
Language: en

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- [Voiceover] Hello
Grammarians. Hello Paige.

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- [Paige] Hi, David.

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- [Dave] So we have
three different sentence

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varieties that we're
going to talk about today.

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- [Paige] Okay.

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- [Dave] Here are their three flavors.

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Flavor number one, declarative sentences.

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Flavor number two,
interrogative sentences.

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And flavor number three,
imperative sentences.

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Those are all pretty
long and wibbly words.

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- [Paige] Seriously.

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- [Dave] But we will address
each one of them in turn.

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Paige, if you please, what
is a declarative sentence?

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- [Paige] A declarative sentence is a type

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of sentence that just
states a fact or an opinion,

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I suppose, but it just makes a statement.

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So that would be something like

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it is a beautiful day.

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- [Dave] It is a beautiful day, Paige.

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We can also use declarative sentences

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to get across any kind of information.

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This is what we call
exposition in writing.

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- [Paige] Righ. Yeah.

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- [Dave] So we can say
Lavender hated baseball.

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You know, you could start
a short story with that.

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- [Paige] Right, that's-
- [Dave] I challenge you to.

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- [Paige] Just a fact about Lavender.

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- [Dave] That's a fact about Lavender.

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So a declarative sentence is a statement.

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Just straight up.

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- [Paige] Yep.

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- [Dave] An interrogative
sentence is a question.

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So it asks a question.

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- [Paige] It's just a
fancy word for a question.

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- [Dave] Right.
- [Paige] Okay.

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- [Dave] So an example of
an interrogative sentence

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would be where did you go last night?

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- [Paige] Right.

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- [Dave] Or how is he
still singing that note?

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- [Paige] I have no idea.

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- [Dave] Incredible breath control

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So that's what an
interrogative question is.

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- [Paige] Right.

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It's like being interrogated.

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That's, like, a similar
word to interrogative,

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is just having a lot of questions asked.

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- [Dave] Like really aggressively.

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- [Paige] Yeah, it's not
a very positive thing.

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- [Dave] Paige, what did
you do with the cheese?

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- [Paige] I don't know. (laughs)

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- [Dave] Paige, why are you
still eating the cheese?

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- [Paige] I'm not.

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- [Dave] Paige, I know
you stole the cheese.

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Finally, the third kind of sentence

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we want to talk about
today is the imperative.

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An imperative is a command.

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- [Paige] Right, so when you
tell someone to do something.

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- [Dave] So a command like,
Paige, follow that bunny!

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(laughs)

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- [Paige] And the bunny stole the cheese.

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- [Dave] Yeah.

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So this is one of those
sentences that doesn't

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have a subject that is
literally spoken out loud.

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- [Paige] Right, it's just implied.

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You know, if you're saying that to me,

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I know that I am the subject.

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- [Dave] Right. So it's
you follow that bunny.

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- [Paige] Right.

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- [Dave] But the you is just not spoken.

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Or, if you're not into
bunny following, you know,

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something like remember
to wash the dishes,

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you're still being commanded to remember.

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- [Paige] Yeah, yeah.

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- [Dave] So, yeah,
that's our, those are our

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three sentence types.

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- [Paige] Yeah.

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Declarative is a statement.

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Interrogative is a question,

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and imperative is a command.

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- [Dave] So, Paige, I think
we can recast our slogan

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in each of these three types of sentence.

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- [Paige] Okay.

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- [Dave] So, okay, so declarative, right?

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That's what it usually
is, declarative form is

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you can learn anything.

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- [Paige] Okay.

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- [Dave] We can make it a
question, so interrogative's

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can you learn anything?

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- [Paige] Right.

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- [Dave] The answer is yes.
- [Paige] Yes.

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- [Dave] And the imperative,
we wanna make it a command,

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would be what, Paige?

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- [Paige] Learn anything!

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- [Dave] Yeah!

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So you can do any of those three.

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- [Paige] Sure.

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- [Dave] David out.

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- [Paige] Paige out.


Subject, direct object, and indirect object

WEBVTT
Kind: captions
Language: en

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- [Voiceover] Hello, grammarians.

00:00:01.054 --> 00:00:01.887
Hello, Rosie.

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- [Voiceover] Hi, David.

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- [Voiceover] So, today
we're gonna be talking about

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subject, direct object,
and indirect object,

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and identifying those within a sentence,

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but first, I suppose we should figure out

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what those things are.

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So, we've talked about
what subjects are before,

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but let's review it again really quickly.

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So, a subject is a noun or a pronoun

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that performs the verb in a sentence.

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So, in the sentence,

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Chris ate cereal,

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Chris is the subject,

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because Chris is the noun or pronoun

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that is performing the verb, ate.

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Rosie, what is a direct object?

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- [Voiceover] So, a direct object is

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the main thing in the sentence that is

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being acted upon,

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so in this sentence, Chris ate cereal,

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cereal would be the direct object,

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because it's the thing

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being acted upon, it's being eaten.

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- [Voiceover] So, every
sentence has to have a subject,

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so subject is critical,

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but direct objects and
indirect objects less so.

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- [Voiceover] Right.
- [Voiceover] So, you know,

00:00:59.876 --> 00:01:02.047
as a sentence, we could just
have "Chris ate", right?

00:01:02.047 --> 00:01:02.880
- [Voiceover] Right.

00:01:02.880 --> 00:01:04.362
- [Voiceover] But if we want
to bring in this direct object,

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we can say Chris ate cereal.

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So, who's doing the eating?

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Chris.

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What is the thing that was eaten?

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Cereal.

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So, this seems like it would cover

00:01:15.350 --> 00:01:19.482
most interactions between
objects and people,

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but then we have this other
thing, indirect object.

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What's that about?

00:01:23.078 --> 00:01:27.001
- [Voiceover] So, an
indirect object is often...

00:01:27.001 --> 00:01:30.188
It's kind of signifying
a recipient of something,

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so it's like another thing in a sentence

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that might be acted upon.

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- [Voiceover] So, let's
see if we can come up

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with some examples for that,

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cause we have this direct object,

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which is this thing being acted upon,

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and then the indirect object
is also being acted upon,

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but it's being acted upon
in, like, a giving way?

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Let's see if we can figure this out.

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Alright, so we have this
sentence, straightforward,

00:01:52.167 --> 00:01:53.815
Althea threw a frisbee.

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So, we've got subject here,

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and we've got direct object here.

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Who's doing the throwing?

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Althea.

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What did she throw?

00:01:59.984 --> 00:02:00.817
A frisbee.

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But, what if we have the sentence

00:02:02.882 --> 00:02:05.842
Althea threw me a frisbee?

00:02:05.842 --> 00:02:08.020
Well, we know from context,

00:02:08.020 --> 00:02:10.118
because we have the word frisbee in here,

00:02:10.118 --> 00:02:13.078
that Althea is not
hurling me, bodily, right?

00:02:13.078 --> 00:02:15.762
She's not chucking me across
a field for a dog to catch.

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But we do know that the
subject of the sentence

00:02:17.741 --> 00:02:20.441
is Althea, and we know
that the direct object

00:02:20.441 --> 00:02:23.074
of the sentence is frisbee,

00:02:23.074 --> 00:02:24.514
but where is that frisbee going?

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Well, it's going to me.

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Okay, so we've got this,
is the direct object,

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this is the subject,

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and this is the indirect object.

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So, the pronoun, me,

00:02:35.844 --> 00:02:39.440
is the recipient of the
direct object, the frisbee.

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Rosie, would you read me
this sentence, please?

00:02:41.925 --> 00:02:44.438
- [Voiceover] Wanda
gave Louie a gift card.

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- [Voiceover] That's very nice of her.

00:02:45.817 --> 00:02:46.650
- [Voiceover] Yeah.

00:02:46.650 --> 00:02:49.415
- [Voiceover] Okay, so,
walk me through this, then.

00:02:49.415 --> 00:02:51.066
What is going on in this sentence?

00:02:51.066 --> 00:02:52.083
What are the relationships

00:02:52.083 --> 00:02:54.321
between the components of this sentence?

00:02:54.321 --> 00:02:55.154
- [Voiceover] Okay.

00:02:55.154 --> 00:02:56.498
So, we have two people,

00:02:56.498 --> 00:02:59.441
and the first person listed is
the subject of the sentence,

00:02:59.441 --> 00:03:01.456
because she's doing an action.

00:03:01.456 --> 00:03:02.605
- [Voiceover] Right,
she's doing the giving.

00:03:02.605 --> 00:03:03.794
- [Voiceover] Right.

00:03:03.794 --> 00:03:06.801
Then we have the direct
object, which is a gift card.

00:03:06.801 --> 00:03:08.971
- [Voiceover] Okay, that's
the object that she gave.

00:03:08.971 --> 00:03:10.625
- [Voiceover] Yeah, that's
something she's giving.

00:03:10.625 --> 00:03:14.385
She has a direct relationship
with that, but she...

00:03:14.385 --> 00:03:18.384
The gift card has a
recipient, and that's Louie,

00:03:18.384 --> 00:03:20.338
and he's the indirect object.

00:03:20.338 --> 00:03:21.374
- [Voiceover] I think
another way to identify

00:03:21.374 --> 00:03:23.768
whether or not a word is the
indirect object in a sentence

00:03:23.768 --> 00:03:25.724
is to see if you can pull it out

00:03:25.724 --> 00:03:28.031
and stick it on the end of the sentence,

00:03:28.031 --> 00:03:30.057
as it currently stands,
with a preposition,

00:03:30.057 --> 00:03:32.724
and see if it still makes sense.

00:03:33.754 --> 00:03:36.946
In this case, to Louie is
no longer what we would

00:03:36.946 --> 00:03:39.807
traditionally consider an indirect object.

00:03:39.807 --> 00:03:41.140
So, if we've got

00:03:41.981 --> 00:03:43.757
Wanda gave a gift card to Louie,

00:03:43.757 --> 00:03:47.228
Wanda is the subject, gift
card is the direct object,

00:03:47.228 --> 00:03:48.811
and then we can see

00:03:49.976 --> 00:03:53.991
to Louie is now this
adverbial prepositional phrase

00:03:53.991 --> 00:03:55.842
that modifies gave.

00:03:55.842 --> 00:03:58.378
It's the manner in which
she gave it to Louie,

00:03:58.378 --> 00:03:59.889
and if we switched it out,

00:03:59.889 --> 00:04:03.896
if we said Wanda gave Louie to gift card,

00:04:03.896 --> 00:04:05.919
that doesn't make sense at all.

00:04:05.919 --> 00:04:08.280
So, to review, the subject is the noun

00:04:08.280 --> 00:04:11.454
or pronoun that performs
a verb in a sentence.

00:04:11.454 --> 00:04:12.754
- [Voiceover] The direct object

00:04:12.754 --> 00:04:14.471
is the thing that's acted upon.

00:04:14.471 --> 00:04:15.802
- [Voiceover] And the indirect object is

00:04:15.802 --> 00:04:18.433
the recipient of that direct object,

00:04:18.433 --> 00:04:21.472
it's the thing that
gets the direct object.

00:04:21.472 --> 00:04:24.527
In the case of Althea threw me a frisbee,

00:04:24.527 --> 00:04:27.417
the pronoun me is the indirect object.

00:04:27.417 --> 00:04:29.958
In the case of Wanda
gave Louie a gift card,

00:04:29.958 --> 00:04:31.781
Louie is the indirect object.

00:04:31.781 --> 00:04:34.773
He gets the gift card, I get the frisbee.

00:04:34.773 --> 00:04:35.606
- [Voiceover] Right.

00:04:35.606 --> 00:04:36.537
- [Voiceover] But, as subjects,

00:04:36.537 --> 00:04:38.134
direct object, and indirect objects,

00:04:38.134 --> 00:04:39.311
you can learn anything.

00:04:39.311 --> 00:04:40.144
David out.

00:04:40.144 --> 00:04:42.144
- [Voiceover] Rosie out.


Subject-verb agreement

WEBVTT
Kind: captions
Language: en

00:00:00.182 --> 00:00:02.424
- [Voiceover] Hello Grammarians,
today we're going to talk

00:00:02.424 --> 00:00:04.630
about subject-verb agreement.

00:00:04.630 --> 00:00:07.355
What this is, is the idea
that you want your subject

00:00:07.355 --> 00:00:11.292
and your verb to get along in a sentence.

00:00:11.292 --> 00:00:15.364
What agreement is, in grammar, is the art

00:00:15.364 --> 00:00:18.726
of making sure that sentence
parts connect with one another

00:00:18.726 --> 00:00:20.290
in the right way.

00:00:20.290 --> 00:00:24.457
It's making sure that a square
peg goes in a square hole.

00:00:25.433 --> 00:00:27.507
Right, not a square peg in a round,

00:00:27.507 --> 00:00:28.839
square peg in a triangular hole.

00:00:28.839 --> 00:00:32.807
You want to make sure that the way you

00:00:32.807 --> 00:00:34.224
render your subject

00:00:34.224 --> 00:00:36.782
fits with the way you've
rendered your verb.

00:00:36.782 --> 00:00:38.161
What do I mean by that?

00:00:38.161 --> 00:00:40.244
Let's take this sentence,

00:00:41.470 --> 00:00:42.637
the dog barks.

00:00:44.737 --> 00:00:47.440
We have this subject, the dog,

00:00:47.440 --> 00:00:49.213
and it is singular,

00:00:49.213 --> 00:00:50.310
there's one of it.

00:00:50.310 --> 00:00:53.050
The way this verb is,
the word is conjugated,

00:00:53.050 --> 00:00:54.826
the way this verb is conjugated,

00:00:54.826 --> 00:00:56.959
the way we've assembled, or figured out

00:00:56.959 --> 00:00:58.397
how the verb is going to be

00:00:58.397 --> 00:01:01.402
is also a singular conjugation.

00:01:01.402 --> 00:01:05.569
So, we say the dog barks
and not the dog bark, right?

00:01:08.891 --> 00:01:12.058
This is not standard American English.

00:01:13.941 --> 00:01:15.941
This is the plural form.

00:01:17.665 --> 00:01:20.380
You can say the dogs bark, right,

00:01:20.380 --> 00:01:22.768
because there's more than one dog here

00:01:22.768 --> 00:01:24.939
and this is their verb,

00:01:24.939 --> 00:01:26.354
this is their plural form.

00:01:26.354 --> 00:01:30.258
I know it's kind of strange
that the third person,

00:01:30.258 --> 00:01:33.091
singular form of a verb ends in S.

00:01:34.968 --> 00:01:37.485
Like, if English made sense--

00:01:37.485 --> 00:01:39.330
OK, like, if I ran the zoo, right,

00:01:39.330 --> 00:01:41.552
I would want it to work like, this,

00:01:41.552 --> 00:01:43.313
the dogs barks, right,

00:01:43.313 --> 00:01:44.880
because there's an S, there's multiple.

00:01:44.880 --> 00:01:49.047
Unfortunately, for many weird
reasons, and the history

00:01:50.230 --> 00:01:53.790
of English, it didn't work out that way.

00:01:53.790 --> 00:01:55.812
A third person singular verb

00:01:55.812 --> 00:01:57.562
usually ends in an S.

00:01:59.904 --> 00:02:02.737
Right, I talk that's first person.

00:02:05.327 --> 00:02:07.494
Third person is she talks.

00:02:11.102 --> 00:02:11.935
We eat.

00:02:15.156 --> 00:02:18.116
That's plural first person.

00:02:18.116 --> 00:02:19.699
They eat, see no S.

00:02:20.956 --> 00:02:22.623
It's only this weird

00:02:23.508 --> 00:02:28.124
third person singular, here,
that's got that S on the end.

00:02:28.124 --> 00:02:29.905
So, if you're trying to figure out

00:02:29.905 --> 00:02:31.507
how to make something agree,

00:02:31.507 --> 00:02:33.838
if you're unsure as you're writing,

00:02:33.838 --> 00:02:35.756
so if you're looking at a sentence like

00:02:35.756 --> 00:02:37.398
the dogs bark.

00:02:37.398 --> 00:02:38.937
And, you can't figure out if it's suppose

00:02:38.937 --> 00:02:41.575
to be the dogs bark or the dog barks,

00:02:41.575 --> 00:02:43.327
or the dogs barks,

00:02:43.327 --> 00:02:47.176
as yourself first, what is
the subject of the sentence?

00:02:47.176 --> 00:02:48.800
So, first find the subject,

00:02:48.800 --> 00:02:51.017
and then ask yourself

00:02:51.017 --> 00:02:52.651
is it singular or plural.

00:02:52.651 --> 00:02:55.125
Is is S or P, is it salt or is it pepper?

00:02:55.125 --> 00:02:57.261
And, then if you can remember that,

00:02:57.261 --> 00:02:59.347
then just remember

00:02:59.347 --> 00:03:03.744
that singular S usually
results in another S.

00:03:03.744 --> 00:03:07.245
So, if it's the dog, and that's singular,

00:03:07.245 --> 00:03:10.512
then you're gonna want
to put that S over here.

00:03:10.512 --> 00:03:12.968
So, if the subject isn't
noun but a pronoun,

00:03:12.968 --> 00:03:14.004
same question.

00:03:14.004 --> 00:03:16.098
Is it singular or plural?

00:03:16.098 --> 00:03:18.406
I is singular, there's only one me.

00:03:18.406 --> 00:03:20.574
We is plural, there's many of us.

00:03:20.574 --> 00:03:22.885
And, if it's singular third person,

00:03:22.885 --> 00:03:25.885
so like she, he, it, end it in an S.

00:03:27.587 --> 00:03:30.010
Another thing to remember, is that most

00:03:30.010 --> 00:03:32.677
what we call indefinite pronouns

00:03:34.331 --> 00:03:35.967
are third person singular.

00:03:35.967 --> 00:03:38.387
So, if you wanted to ask whether or not

00:03:38.387 --> 00:03:40.728
anyone knows the way to
San Jose as a question,

00:03:40.728 --> 00:03:42.644
but you're not sure whether or not

00:03:42.644 --> 00:03:45.281
it would be does anyone
know the way to San Jose,

00:03:45.281 --> 00:03:47.814
or do anyone know the way to San Jose?

00:03:47.814 --> 00:03:51.267
Well, the work anyone is
third person singular,

00:03:51.267 --> 00:03:53.696
and all though do is an irregular verb,

00:03:53.696 --> 00:03:55.433
we still kind of hold to the idea

00:03:55.433 --> 00:03:57.789
of the third person
singular verb ends in an S.

00:03:57.789 --> 00:04:00.789
So, it's a z sound, written as an S,

00:04:01.927 --> 00:04:03.677
so we would say does.

00:04:11.990 --> 00:04:14.707
Does anyone know as opposed to

00:04:14.707 --> 00:04:17.597
if it were in the plural.

00:04:17.597 --> 00:04:19.097
Do we know, right?

00:04:21.529 --> 00:04:24.446
So, does is singular, do is plural.

00:04:25.298 --> 00:04:27.396
And, that's kind of the basic idea

00:04:27.396 --> 00:04:28.916
of subject-verb agreement,

00:04:28.916 --> 00:04:30.488
cause you want to make sure

00:04:30.488 --> 00:04:33.498
that the number of things in your subject

00:04:33.498 --> 00:04:37.032
matches up with the
number in your predicate.

00:04:37.032 --> 00:04:39.372
So, is the subject singular or plural?

00:04:39.372 --> 00:04:41.036
If it's third person singular,

00:04:41.036 --> 00:04:43.000
the verb probably ends in an S,

00:04:43.000 --> 00:04:45.794
even though the third person singular

00:04:45.794 --> 00:04:47.877
noun or pronoun does not.

00:04:50.037 --> 00:04:52.660
You can learn anything, David out.


Simple and compound sentences

WEBVTT
Kind: captions
Language: en

00:00:00.854 --> 00:00:02.174
- [Voiceover] Hello Grammarians.

00:00:02.174 --> 00:00:03.007
Hello Paige.

00:00:03.007 --> 00:00:04.296
- [Voiceover] Hi David.

00:00:04.296 --> 00:00:06.148
- [Voiceover] I say hello to you

00:00:06.148 --> 00:00:08.415
and I say hello to the grammarians.

00:00:08.415 --> 00:00:11.137
- [Voiceover] That was an
interesting thing to say.

00:00:11.137 --> 00:00:12.925
- [Voiceover] Yeah, it's cause
there's a compound sentence.

00:00:12.925 --> 00:00:13.758
- [Voiceover] I see.

00:00:13.758 --> 00:00:17.476
- [Voiceover] So there's this
distinction made in grammar,

00:00:17.476 --> 00:00:21.162
between simple and compound sentences.

00:00:21.162 --> 00:00:22.869
And today Paige, you and I are going

00:00:22.869 --> 00:00:24.535
to cover those differences.

00:00:24.535 --> 00:00:25.583
- [Voiceover] Let's do it.

00:00:25.583 --> 00:00:29.127
- [Voiceover] So, a simple
sentence is really just

00:00:29.127 --> 00:00:31.333
what it says on the tin.

00:00:31.333 --> 00:00:35.295
A simple sentence consists of one subject

00:00:35.295 --> 00:00:37.721
and one predicate, and that's it.

00:00:37.721 --> 00:00:38.554
- [Voiceover] Right.

00:00:38.554 --> 00:00:39.387
- [Voiceover] So in the sentence,

00:00:39.387 --> 00:00:41.817
I bought my friends some candy,

00:00:41.817 --> 00:00:44.650
alright we got our one subject, I.

00:00:45.738 --> 00:00:47.912
And then we have our one predicate,

00:00:47.912 --> 00:00:49.566
bought my friends some candy.

00:00:49.566 --> 00:00:50.553
- [Voiceover] Mhmm.

00:00:50.553 --> 00:00:51.639
- [Voiceover] Now all of this together is

00:00:51.639 --> 00:00:55.023
what we call an independent clause.

00:00:55.023 --> 00:00:56.953
I don't wanna hit that too hard right now.

00:00:56.953 --> 00:01:00.203
But you know, when you have this set of

00:01:01.460 --> 00:01:03.106
subject and a predicate together,

00:01:03.106 --> 00:01:04.476
and it can be a sentence, that's called

00:01:04.476 --> 00:01:06.643
an independent clause.

00:01:06.643 --> 00:01:08.084
I'm not even gonna write that down.

00:01:08.084 --> 00:01:08.917
- [Voiceover] Yeah.

00:01:08.917 --> 00:01:12.493
- [Voiceover] But a compound
sentence is basically

00:01:12.493 --> 00:01:16.109
two or more simple
sentences joined together.

00:01:16.109 --> 00:01:20.276
So that would be two
subjects plus two predicates.

00:01:23.679 --> 00:01:26.785
Or more, two, three, a bajillion.

00:01:26.785 --> 00:01:27.618
- [Voiceover] Sure.

00:01:27.618 --> 00:01:29.171
- [Voiceover] That would be
a very long sentence to read,

00:01:29.171 --> 00:01:30.085
but you could do it, it would be

00:01:30.085 --> 00:01:33.199
a very very compound sentence.

00:01:33.199 --> 00:01:37.366
So I visited the beach and
I got a really bad sunburn.

00:01:38.584 --> 00:01:42.418
When we're looking at this,
this is really two sentences

00:01:42.418 --> 00:01:46.034
together, joined by
the comma and this and.

00:01:46.034 --> 00:01:48.701
Alright, so we have our subject,

00:01:49.691 --> 00:01:53.888
I visited the beach, I
got a really bad sunburn.

00:01:53.888 --> 00:01:55.360
And we have our two predicates,

00:01:55.360 --> 00:01:59.193
I visited the beach, got
a really bad sunburn.

00:02:00.135 --> 00:02:01.832
- [Voiceover] So the
subject in both these cases

00:02:01.832 --> 00:02:04.401
is I right, but it's sort of separate.

00:02:04.401 --> 00:02:07.684
It's like, I'm doing
two different actions.

00:02:07.684 --> 00:02:08.830
- [Voiceover] Correct.

00:02:08.830 --> 00:02:11.016
- [Voiceover] What's
important is even if it's

00:02:11.016 --> 00:02:14.746
the same subject, if it's I both times.

00:02:14.746 --> 00:02:15.741
Well I don't know how to say this,

00:02:15.741 --> 00:02:18.565
but just, if it were, I visited the beach

00:02:18.565 --> 00:02:20.170
and got a really bad sunburn.

00:02:20.170 --> 00:02:21.215
- [Voiceover] Then it
would be a simple sentence.

00:02:21.215 --> 00:02:22.597
- [Voiceover] Then it's simple.

00:02:22.597 --> 00:02:23.868
- [Voiceover] Okay so
Paige, I'm looking at this

00:02:23.868 --> 00:02:25.351
and I see I twice.

00:02:25.351 --> 00:02:27.972
What if I wanted to condense
this sentence further?

00:02:27.972 --> 00:02:29.293
- [Voiceover] Okay.

00:02:29.293 --> 00:02:31.650
- [Voiceover] What does that give us?

00:02:31.650 --> 00:02:34.970
Is this a simple sentence
or a compound sentence?

00:02:34.970 --> 00:02:38.140
Because this looks like
what you would call

00:02:38.140 --> 00:02:40.590
a compound predicate.

00:02:40.590 --> 00:02:44.165
- [Voiceover] Right, since
there's only one subject

00:02:44.165 --> 00:02:47.158
in this sentence, there's only
I and it's only said once.

00:02:47.158 --> 00:02:49.224
Right, you don't have, I visited the beach

00:02:49.224 --> 00:02:51.633
and I got a really bad sunburn.

00:02:51.633 --> 00:02:53.035
That whole thing, visited the beach

00:02:53.035 --> 00:02:54.396
and got a really bad sunburn,

00:02:54.396 --> 00:02:58.570
is you're right, it is
a compound predicate.

00:02:58.570 --> 00:03:00.550
- [Voiceover] But what
you're saying is I couldn't

00:03:00.550 --> 00:03:03.792
divide this up into two sentences,

00:03:03.792 --> 00:03:05.632
unless I put in another subject.

00:03:05.632 --> 00:03:08.212
Right, you can say, I visited the beach,

00:03:08.212 --> 00:03:11.501
and that could be a sentence on its own.

00:03:11.501 --> 00:03:15.483
But you can't say, and
got a really bad sunburn,

00:03:15.483 --> 00:03:16.978
as its own sentence.

00:03:16.978 --> 00:03:20.623
- [Voiceover] Okay, so both
of these things are simple.

00:03:20.623 --> 00:03:23.509
So even though this is
a compound predicate,

00:03:23.509 --> 00:03:26.780
it's technically one predicate.

00:03:26.780 --> 00:03:28.694
- [Voiceover] Right, it's --

00:03:28.694 --> 00:03:32.117
- [Voiceover] And even if I'd written,

00:03:32.117 --> 00:03:33.804
Paige and I visited the beach

00:03:33.804 --> 00:03:35.559
and I got a really bad sunburn,

00:03:35.559 --> 00:03:38.241
that would still be a compound subject,

00:03:38.241 --> 00:03:40.517
but it wouldn't be two
sentences squished together,

00:03:40.517 --> 00:03:43.260
it would be one kind of long sentence.

00:03:43.260 --> 00:03:44.337
- [Voiceover] Right.

00:03:44.337 --> 00:03:48.504
You can have a compound subject
or a compound predicate,

00:03:49.384 --> 00:03:52.310
but that doesn't make
it a compound sentence.

00:03:52.310 --> 00:03:53.378
What makes it a compound sentence,

00:03:53.378 --> 00:03:56.629
is you have two parts that
can stand on their own

00:03:56.629 --> 00:03:58.701
as individual sentences, and they're

00:03:58.701 --> 00:04:01.493
sort of being put together.

00:04:01.493 --> 00:04:03.423
- [Voiceover] So let me
change what I wrote here,

00:04:03.423 --> 00:04:06.300
to just say, instead of two
subjects and two predicates.

00:04:06.300 --> 00:04:07.661
Cause I think that's confusing in light of

00:04:07.661 --> 00:04:11.828
this information, let's just
say it is two simple sentences.

00:04:13.716 --> 00:04:17.646
- [Voiceover] Right, or
two independent clauses.

00:04:17.646 --> 00:04:19.149
You know, that terminology.

00:04:19.149 --> 00:04:21.071
- [Voiceover] Or two, yeah.

00:04:21.071 --> 00:04:23.549
And if you don't, never
fear, we'll cover it,

00:04:23.549 --> 00:04:26.008
and you can learn anything.

00:04:26.008 --> 00:04:26.841
David out.

00:04:26.841 --> 00:04:28.581
- [Voiceover] Paige out.


What is a sentence?

WEBVTT
Kind: captions
Language: en

00:00:00.000 --> 00:00:01.727
- [Voiceover] Hello
grammarians, hello Paige.

00:00:01.727 --> 00:00:02.560
- [Voiceover] Hi, David.

00:00:02.560 --> 00:00:05.116
- [Voiceover] So today
we're gonna tackle this idea

00:00:05.116 --> 00:00:08.116
of what is a sentence, as we go into

00:00:09.290 --> 00:00:13.040
this realm of language
that is called syntax.

00:00:15.456 --> 00:00:19.623
And syntax is this concept of,
basically grammatical order.

00:00:20.711 --> 00:00:23.822
What this word syntax
literally means in Greek,

00:00:23.822 --> 00:00:27.135
is, you know, putting
together and arranging, right,

00:00:27.135 --> 00:00:30.302
so it just means ordering of language.

00:00:33.224 --> 00:00:34.530
- [Voiceover] So that's,
like, what a sentence is.

00:00:34.530 --> 00:00:35.363
- [Voiceover] That's what a sentence is,

00:00:35.363 --> 00:00:36.521
it's what a sentence is, it's what

00:00:36.521 --> 00:00:39.357
the components of a sentence are.

00:00:39.357 --> 00:00:43.890
And we'll go into all of
that in much greater detail,

00:00:43.890 --> 00:00:45.685
but in order to do that, first of all

00:00:45.685 --> 00:00:49.875
we have to figure out what
a sentence actually is.

00:00:49.875 --> 00:00:52.667
So, the definition that you
and I came up with, Paige,

00:00:52.667 --> 00:00:56.138
is that a sentence is a
grammatically complete idea.

00:00:56.138 --> 00:00:57.805
- [Voiceover] Right.

00:00:59.166 --> 00:01:03.295
It's a bunch of words that
say one complete thing.

00:01:03.295 --> 00:01:04.445
- [Voiceover] So, all sentences have

00:01:04.445 --> 00:01:06.787
a noun or pronoun component,
- [Voiceover] Mmm-hmm.

00:01:06.787 --> 00:01:10.954
- [Voiceover] Right, and that's
what we call the subject.

00:01:13.697 --> 00:01:17.864
And then we have the verb
part, which is the predicate.

00:01:20.754 --> 00:01:21.587
- [Voiceover] So a sentence has,

00:01:21.587 --> 00:01:24.298
it has to have like, a
thing, or a noun or pronoun.

00:01:24.298 --> 00:01:25.482
- [Voiceover] Sure, that's the subject.

00:01:25.482 --> 00:01:27.653
- [Voiceover] Yeah, and
something that it's doing.

00:01:27.653 --> 00:01:29.252
- [Voiceover] Sure, that's the predicate.

00:01:29.252 --> 00:01:30.331
- [Voiceover] Yeah.
- [Voiceover] Okay.

00:01:30.331 --> 00:01:33.154
So let's say that we've got this sentence,

00:01:33.154 --> 00:01:34.571
the great big dog

00:01:38.583 --> 00:01:39.833
licked my face.

00:01:44.275 --> 00:01:47.235
Here is our sentence, what is the subject?

00:01:47.235 --> 00:01:49.747
- [Voiceover] Subject
is the great big dog.

00:01:49.747 --> 00:01:52.011
- [Voiceover] Alright, and that means that

00:01:52.011 --> 00:01:53.503
everything that's not the subject

00:01:53.503 --> 00:01:55.134
is part of the predicate, right?

00:01:55.134 --> 00:01:56.149
- [Voiceover] Mmm-hmm.

00:01:56.149 --> 00:01:58.845
- [Voiceover] So, licked
my face is the predicate.

00:01:58.845 --> 00:02:01.536
So this is the noun chunk that is

00:02:01.536 --> 00:02:04.284
performing the action of the sentence.

00:02:04.284 --> 00:02:05.435
- [Voiceover] You got it, yeah.

00:02:05.435 --> 00:02:07.045
- [Voiceover] Cool.

00:02:07.045 --> 00:02:09.081
So, all sentences have
to have this, right?

00:02:09.081 --> 00:02:10.340
- [Voiceover] Yeah, they have to have

00:02:10.340 --> 00:02:13.650
a subject and a predicate,
these two separate parts.

00:02:13.650 --> 00:02:17.817
- [Voiceover] So if you said,
if you asked a question like,

00:02:19.010 --> 00:02:20.841
Are you named David?

00:02:20.841 --> 00:02:21.882
- [Voiceover] Okay,

00:02:21.882 --> 00:02:22.753
- [Voiceover] If you asked that of me,

00:02:22.753 --> 00:02:23.586
- [Voiceover] Mmm-hmm,

00:02:23.586 --> 00:02:24.647
- [Voiceover] Which, go ahead.

00:02:24.647 --> 00:02:25.691
- [Voiceover] Are you named David?

00:02:25.691 --> 00:02:27.274
- [Voiceover] I am.

00:02:28.236 --> 00:02:30.287
Is this a sentence, it's really short.

00:02:30.287 --> 00:02:31.274
- [Voiceover] It is very short.

00:02:31.274 --> 00:02:33.603
But, see, "I" is a pronoun,
- [Voiceover] Okay,

00:02:33.603 --> 00:02:35.233
- [Voiceover] So that can be the subject.

00:02:35.233 --> 00:02:36.100
- [Voiceover] That's our subject.

00:02:36.100 --> 00:02:37.081
- [Voiceover] And, "am" is a verb.

00:02:37.081 --> 00:02:40.109
So it has a subject and a predicate.

00:02:40.109 --> 00:02:42.855
- [Voiceover] So this is
the noun or pronoun part.

00:02:42.855 --> 00:02:46.158
And this is the action
that it is performing.

00:02:46.158 --> 00:02:48.427
Although "am" or "being"
isn't really an action,

00:02:48.427 --> 00:02:51.413
it's more of a linking verb.
- [Voiceover] Sure.

00:02:51.413 --> 00:02:53.350
- [Voiceover] But it's still a verb.

00:02:53.350 --> 00:02:54.234
- [Voiceover] Okay.

00:02:54.234 --> 00:02:55.205
- [Voiceover] Okay, so this is, this is

00:02:55.205 --> 00:02:56.122
the predicate then, for sure.

00:02:56.122 --> 00:02:57.141
- [Voiceover] Yeah.

00:02:57.141 --> 00:02:59.979
- [Voiceover] Okay, so Paige.

00:02:59.979 --> 00:03:02.201
Let's say I dropped a muffin.

00:03:02.201 --> 00:03:03.034
- [Voiceover] Right,

00:03:03.034 --> 00:03:06.150
- [Voiceover] And you told
me, pick up that muffin.

00:03:06.150 --> 00:03:07.525
- [Voiceover] Uh-huh.

00:03:07.525 --> 00:03:09.135
- [Voiceover] That sentence
doesn't seem to have,

00:03:09.135 --> 00:03:11.468
just let me write that down.

00:03:19.510 --> 00:03:21.927
That sentence doesn't
seem to have a subject.

00:03:21.927 --> 00:03:24.844
I see how all of this is predicate.

00:03:25.938 --> 00:03:27.746
- [Voiceover] Right, pick
up is a verb, and then,

00:03:27.746 --> 00:03:29.169
- [Voiceover] And then
the muffin is the thing

00:03:29.169 --> 00:03:31.972
that's being picked up,
like that's all one thing.

00:03:31.972 --> 00:03:34.906
Where's, what goes in the blue box?

00:03:34.906 --> 00:03:36.687
- [Voiceover] I see, so when
we have a sentence like this,

00:03:36.687 --> 00:03:38.997
where I'm telling you to do something,

00:03:38.997 --> 00:03:39.830
- [Voiceover] Mmm-hmm,

00:03:39.830 --> 00:03:40.945
- [Voiceover] There
doesn't always have to be

00:03:40.945 --> 00:03:43.156
a subject said out loud.

00:03:43.156 --> 00:03:44.199
- [Voiceover] Okay.

00:03:44.199 --> 00:03:45.918
- [Voiceover] This is
like an order, right?

00:03:45.918 --> 00:03:47.969
I'm telling you you have
to pick up that muffin.

00:03:47.969 --> 00:03:49.017
- [Voiceover] So this is kinda like

00:03:49.017 --> 00:03:51.434
an invisible, secret subject.

00:03:52.650 --> 00:03:54.677
- [Voiceover] Right, the
subject really is you.

00:03:54.677 --> 00:03:55.510
- [Voiceover] Okay,

00:03:55.510 --> 00:03:57.078
- [Voiceover] You pick up that muffin,

00:03:57.078 --> 00:03:58.430
but I don't have to say it out loud.

00:03:58.430 --> 00:03:59.904
- [Voiceover] Because I know
that you're talking to me.

00:03:59.904 --> 00:04:01.535
Because I can tell 'cause
you're looking at me,

00:04:01.535 --> 00:04:03.215
and you're yelling at me about a muffin.

00:04:03.215 --> 00:04:04.055
- [Voiceover] Yes, I am.

00:04:04.055 --> 00:04:06.009
- [Voiceover] So, a sentence is

00:04:06.009 --> 00:04:10.124
a grammatically complete
idea or expression.

00:04:10.124 --> 00:04:10.957
- [Voiceover] Mmm-hmm.

00:04:10.957 --> 00:04:13.387
- [Voiceover] And it has to
have a noun or pronoun part,

00:04:13.387 --> 00:04:15.315
which we call the subject,
and it has to have

00:04:15.315 --> 00:04:17.213
a verb and all its baggage part,

00:04:17.213 --> 00:04:19.245
which is what we call the predicate.

00:04:19.245 --> 00:04:24.167
And sometimes that subject
can sort of be implied,

00:04:24.167 --> 00:04:27.445
or invisible, as in the
command. "Pick up that muffin!"

00:04:27.445 --> 00:04:28.959
- [Voiceover] Right.
- [Voiceover] Cool.

00:04:28.959 --> 00:04:30.496
You can learn anything, David out.

00:04:30.496 --> 00:04:32.496
- [Voiceover] Paige out.


The Monroe Doctrine

WEBVTT
Kind: captions
Language: en

00:00:00.400 --> 00:00:04.817
- On December 2, 1823,
U.S. President James Monroe

00:00:04.817 --> 00:00:08.152
was giving his annual
State of the Union Address

00:00:08.152 --> 00:00:11.440
to Congress when he threw
in a couple of remarks

00:00:11.440 --> 00:00:13.681
about the United States' relationship

00:00:13.681 --> 00:00:15.614
with the powers of Europe.

00:00:15.614 --> 00:00:18.121
He said, "The American continents,

00:00:18.121 --> 00:00:20.412
"by the free and independent condition

00:00:20.412 --> 00:00:22.602
"which they have assumed and maintained,

00:00:22.602 --> 00:00:25.730
"are henceforth not to
be considered as subjects

00:00:25.730 --> 00:00:29.730
"for future colonization
by any European powers.

00:00:30.848 --> 00:00:32.764
"In the wars of the European powers

00:00:32.764 --> 00:00:34.920
"in matters relating to themselves

00:00:34.920 --> 00:00:37.012
"we have never taken any part,

00:00:37.012 --> 00:00:40.472
"nor does it comport
with our policy to do so.

00:00:40.472 --> 00:00:42.822
"We owe it, therefore, to candor

00:00:42.822 --> 00:00:45.209
"and to the amicable relations existing

00:00:45.209 --> 00:00:48.057
"between the United States
and those powers to declare

00:00:48.057 --> 00:00:50.949
"that we should consider
any attempt on their part

00:00:50.949 --> 00:00:54.924
"to extend their system to
any portion of this hemisphere

00:00:54.924 --> 00:00:58.160
"as dangerous to our peace and safety."

00:00:58.160 --> 00:01:01.191
So, basically, in one fell swoop,

00:01:01.191 --> 00:01:05.280
James Monroe told the
crowned heads of Europe

00:01:05.280 --> 00:01:07.613
to stay out of the Americas.

00:01:10.499 --> 00:01:13.406
He said, "As far as I'm concerned,

00:01:13.406 --> 00:01:16.239
"the era of colonization is over."

00:01:20.446 --> 00:01:23.022
Stop giving us the side-eye.

00:01:23.022 --> 00:01:24.918
Stop looking at your
maps and trying to decide

00:01:24.918 --> 00:01:27.589
where you might place
a little colony next.

00:01:27.589 --> 00:01:31.503
No more European
colonization in the Americas.

00:01:31.503 --> 00:01:33.920
What's more, don't interfere.

00:01:40.285 --> 00:01:43.177
The Americas are the
United States' concern

00:01:43.177 --> 00:01:45.550
so we don't want the powers of Europe

00:01:45.550 --> 00:01:48.020
to meddle in any of the affairs

00:01:48.020 --> 00:01:50.322
of Latin America or South America.

00:01:50.322 --> 00:01:52.848
You can keep your system,

00:01:52.848 --> 00:01:55.931
and by system, Monroe meant monarchy,

00:01:58.643 --> 00:01:59.984
out of the Americas.

00:01:59.984 --> 00:02:02.984
This is the hemisphere of democracy.

00:02:04.324 --> 00:02:07.570
So, this is an incredibly bold statement.

00:02:07.570 --> 00:02:10.062
Let's not forget here
that the United States

00:02:10.062 --> 00:02:13.759
is not exactly a world power in 1823.

00:02:13.759 --> 00:02:17.345
They could, at best, be
said to be a minor power,

00:02:17.345 --> 00:02:19.250
even in the Americas.

00:02:19.250 --> 00:02:22.227
The United States is not a
major world military power,

00:02:22.227 --> 00:02:24.503
it's not a major world Navy power.

00:02:24.503 --> 00:02:27.098
Let's remember that in this era,

00:02:27.098 --> 00:02:30.146
having a strong Navy was
tantamount to being able

00:02:30.146 --> 00:02:31.777
to take over the world.

00:02:31.777 --> 00:02:35.402
They're kind of a second-rate nation

00:02:35.402 --> 00:02:38.140
in a second-rate part of the world.

00:02:38.140 --> 00:02:40.147
So, what was the response
when the United States

00:02:40.147 --> 00:02:43.717
made this incredibly bold assertion

00:02:43.717 --> 00:02:46.092
that they would not permit
any more colonization

00:02:46.092 --> 00:02:50.097
or interference in the
Americas from Europe?

00:02:50.097 --> 00:02:51.665
Mmm...

00:02:51.665 --> 00:02:52.498
Crickets.

00:02:53.682 --> 00:02:55.349
Nobody really cared.

00:02:57.707 --> 00:02:59.579
To the established powers of Europe,

00:02:59.579 --> 00:03:02.375
the United States was no
more than a little mosquito,

00:03:02.375 --> 00:03:04.783
buzzing around, maybe
making a lot of noise,

00:03:04.783 --> 00:03:08.148
a bit annoying, but pretty easy to swat.

00:03:08.148 --> 00:03:11.303
No matter how much noise
the United States made,

00:03:11.303 --> 00:03:13.668
the only thing that mattered to

00:03:13.668 --> 00:03:16.595
the great powers of the
world was whether or not

00:03:16.595 --> 00:03:20.762
the United States could
enforce the Monroe Doctrine,

00:03:21.750 --> 00:03:24.571
which with such a weak military presence,

00:03:24.571 --> 00:03:26.024
they certainly could not.

00:03:26.024 --> 00:03:29.357
Nevertheless, the Monroe Doctrine became

00:03:30.567 --> 00:03:34.487
a key facet of American foreign policy

00:03:34.487 --> 00:03:38.378
throughout the 19th century
and into the 20th century.

00:03:38.378 --> 00:03:42.211
It became a justification
for Manifest Destiny

00:03:46.809 --> 00:03:48.979
and would play a major role
in the foreign policies

00:03:48.979 --> 00:03:52.969
of Teddy Roosevelt and
Franklin Delano Roosevelt.

00:03:52.969 --> 00:03:54.928
So, where did the Monroe
Doctrine come from?

00:03:54.928 --> 00:03:56.835
Well, let's take a minute
to look at some of the

00:03:56.835 --> 00:03:59.490
major world events of the time period

00:03:59.490 --> 00:04:03.741
and the major players who brought
the Monroe Doctrine about.

00:04:03.741 --> 00:04:05.824
All right, dateline 1820.

00:04:07.703 --> 00:04:11.869
It has been a bad couple of
years for monarchy in Europe.

00:04:11.869 --> 00:04:15.395
For one thing, the Napoleonic
Wars and the French Revolution

00:04:15.395 --> 00:04:19.075
have been convulsing the powers of Europe

00:04:19.075 --> 00:04:20.575
for several years.

00:04:21.537 --> 00:04:25.861
By 1815, the Revolution
has more or less finished

00:04:25.861 --> 00:04:30.028
and the monarchies of
Europe have been reinstated.

00:04:35.086 --> 00:04:37.679
But, this revolutionary fervor

00:04:37.679 --> 00:04:39.416
coming from the French Revolution,

00:04:39.416 --> 00:04:41.511
coming also from the American Revolution,

00:04:41.511 --> 00:04:42.932
has started to spread.

00:04:42.932 --> 00:04:46.417
So, movements for independence
are now taking hold

00:04:46.417 --> 00:04:47.801
in South America.

00:04:47.801 --> 00:04:51.994
There's a Chilean
movement for independence,

00:04:51.994 --> 00:04:54.649
Argentinian movement for independence,

00:04:54.649 --> 00:04:57.510
Venezuelan movement for independence.

00:04:57.510 --> 00:05:01.260
So, they've kind of
caught the democracy bug.

00:05:03.511 --> 00:05:06.746
The people in the United
States are cheering

00:05:06.746 --> 00:05:09.539
for their southern brethren, saying,

00:05:09.539 --> 00:05:12.072
"Excellent work, picking up democracy,

00:05:12.072 --> 00:05:15.424
"breaking away from
old-fashioned, monarchical,

00:05:15.424 --> 00:05:16.864
"tyrannical Europe.

00:05:16.864 --> 00:05:18.313
"We're totally on your side."

00:05:18.313 --> 00:05:22.469
But it's easier to make an
independence movement happen

00:05:22.469 --> 00:05:27.437
when the home country is
distracted with another war,

00:05:27.437 --> 00:05:29.214
aka the Napoleonic Wars.

00:05:29.214 --> 00:05:31.406
Once the Napoleonic Wars are over,

00:05:31.406 --> 00:05:33.755
the monarchies of Europe start saying,

00:05:33.755 --> 00:05:35.702
"Hmm, you know what?

00:05:35.702 --> 00:05:39.369
"Since Spain is in
control of these nations,

00:05:41.195 --> 00:05:43.666
"now Spain has the time and energy

00:05:43.666 --> 00:05:47.833
"to consider maybe putting
down these revolutions."

00:05:50.952 --> 00:05:53.842
So, they're no longer distracted by war,

00:05:53.842 --> 00:05:56.866
and they have the
manpower and the bandwidth

00:05:56.866 --> 00:06:01.657
to think about maybe trying
to reinstate, or secure,

00:06:01.657 --> 00:06:05.049
Spanish rule in South
America where nations

00:06:05.049 --> 00:06:07.745
have been in the process of revolution.

00:06:07.745 --> 00:06:09.384
Now, we don't know the extent to which

00:06:09.384 --> 00:06:11.055
Spain was actually planning on

00:06:11.055 --> 00:06:12.780
putting these revolutions down,

00:06:12.780 --> 00:06:16.704
but we do know that the
United States and England

00:06:16.704 --> 00:06:19.288
were very concerned that the monarchies

00:06:19.288 --> 00:06:22.121
of the continent-- France and Spain--

00:06:23.020 --> 00:06:26.375
might join together and try to put down

00:06:26.375 --> 00:06:28.303
all of these revolutions.

00:06:28.303 --> 00:06:29.887
Now, wouldn't they want that?

00:06:29.887 --> 00:06:33.748
Well, for the most part, it
kind of came down to markets.

00:06:33.748 --> 00:06:38.157
If you think back to early
American colonial society,

00:06:38.157 --> 00:06:41.990
the economic system was
known as mercantilism.

00:06:43.261 --> 00:06:45.844
Mercantilism is the practice of

00:06:46.739 --> 00:06:50.195
colonies kind of existing to
enrich the mother country.

00:06:50.195 --> 00:06:53.862
So, all trade goes
through the home country.

00:06:56.515 --> 00:07:00.011
That means that the home country
is going to be making sure

00:07:00.011 --> 00:07:02.135
that the colonies are not trading

00:07:02.135 --> 00:07:03.962
with any other international partners

00:07:03.962 --> 00:07:06.634
because they want to be
the ones who are enriched

00:07:06.634 --> 00:07:09.995
by the natural resources of the colonies.

00:07:09.995 --> 00:07:13.970
So, when Chile and Argentina and Venezuela

00:07:13.970 --> 00:07:15.310
revolt from Spain,

00:07:15.310 --> 00:07:19.060
it means that their
markets are now opened up

00:07:20.000 --> 00:07:23.000
to the United States and to England.

00:07:24.691 --> 00:07:27.718
So, England and the United
States are not eager

00:07:27.718 --> 00:07:30.718
to see these new nations be returned

00:07:31.711 --> 00:07:33.691
to their colonial status because,

00:07:33.691 --> 00:07:35.815
thanks to mercantilism, they're not going

00:07:35.815 --> 00:07:37.438
to be able to trade with them anymore.

00:07:37.438 --> 00:07:39.355
With this idea in mind,

00:07:40.377 --> 00:07:42.809
the British Foreign Secretary,

00:07:42.809 --> 00:07:45.059
a man named George Canning,

00:07:46.894 --> 00:07:50.477
approached the American
Secretary of State,

00:07:51.798 --> 00:07:53.298
John Quincy Adams,

00:07:56.145 --> 00:07:57.145
and he said,

00:07:59.022 --> 00:08:02.697
"Why don't we make a joint proclamation

00:08:02.697 --> 00:08:05.963
"between the United
States and Great Britain

00:08:05.963 --> 00:08:08.619
"saying that the powers of Europe

00:08:08.619 --> 00:08:11.216
"should not interfere in the New World.?

00:08:11.216 --> 00:08:13.013
And John Quincy Adams thought,

00:08:13.013 --> 00:08:17.479
"Hmm, I'm not sure if I
like you British folks."

00:08:17.479 --> 00:08:21.562
Remember that the War of
1812 had not taken place

00:08:22.866 --> 00:08:25.315
too long beforehand.

00:08:25.315 --> 00:08:26.762
The United States was not quite ready

00:08:26.762 --> 00:08:29.625
to be friends with the United Kingdom yet.

00:08:29.625 --> 00:08:32.269
And they were a little bit afraid that

00:08:32.269 --> 00:08:36.655
if the United States made a
joint declaration with England

00:08:36.655 --> 00:08:39.542
that it would seem a little bit like

00:08:39.542 --> 00:08:41.919
a flea on the back of a rottweiler saying,

00:08:41.919 --> 00:08:43.600
"Don't mess with us or we'll bite you!"

00:08:43.600 --> 00:08:46.482
The United States didn't
have nearly the strength

00:08:46.482 --> 00:08:48.576
to actually make an equal partnership

00:08:48.576 --> 00:08:50.069
so it might have looked a little bit like

00:08:50.069 --> 00:08:53.383
they were hiding behind the
British in a joint declaration,

00:08:53.383 --> 00:08:57.486
but J.Q.A. thought this
actually still sounded

00:08:57.486 --> 00:09:02.146
like a pretty good plan
so he floated the idea

00:09:02.146 --> 00:09:04.313
to President James Monroe.

00:09:07.790 --> 00:09:10.325
Now, there's kind of a

00:09:10.325 --> 00:09:13.699
movement of nationalism
going on at this time

00:09:13.699 --> 00:09:14.888
in the United States.

00:09:14.888 --> 00:09:16.905
Even though the United States

00:09:16.905 --> 00:09:20.288
didn't technically win the War of 1812,

00:09:20.288 --> 00:09:22.764
they kind of felt like they had.

00:09:22.764 --> 00:09:25.827
So, they're busy kind of creating

00:09:25.827 --> 00:09:30.554
a new nationalist rhetoric
in the United States.

00:09:30.554 --> 00:09:32.893
They're feeling pretty
good about themselves.

00:09:32.893 --> 00:09:37.664
They stood up to their old
foe of Great Britain, and won.

00:09:37.664 --> 00:09:39.133
Or, at the very least, didn't lose,

00:09:39.133 --> 00:09:40.551
but to them it was kind of the same thing.

00:09:40.551 --> 00:09:44.172
So, John Quincy Adams
crafts for James Monroe

00:09:44.172 --> 00:09:46.695
what will become known
as the Monroe Doctrine.

00:09:46.695 --> 00:09:49.232
Now, Monroe is not only concerned about

00:09:49.232 --> 00:09:52.973
the possibility of European
powers coming down here

00:09:52.973 --> 00:09:55.102
and trying to start fights with each other

00:09:55.102 --> 00:09:57.647
over the fate of South America.

00:09:57.647 --> 00:10:00.423
Monroe was also worried about Russia,

00:10:00.423 --> 00:10:04.971
who had recently made some
territorial claims in Canada,

00:10:04.971 --> 00:10:06.465
saying that their territory should come

00:10:06.465 --> 00:10:08.237
all the way down there.

00:10:08.237 --> 00:10:11.598
The Russians have started
putting some forts

00:10:11.598 --> 00:10:14.124
on the coast of California,

00:10:14.124 --> 00:10:16.107
close to modern day San Francisco.

00:10:16.107 --> 00:10:20.684
So, Monroe sees the old
monarchical powers of Europe

00:10:20.684 --> 00:10:24.672
sort of encroaching both from
the north and the south here.

00:10:24.672 --> 00:10:28.172
And so, in 1823, he makes the announcement

00:10:29.160 --> 00:10:30.647
of the Monroe Doctrine.

00:10:30.647 --> 00:10:33.230
He says, "No more colonization.

00:10:34.374 --> 00:10:36.541
"Russia, get out of there.

00:10:38.334 --> 00:10:41.501
"And no more interference, in general.

00:10:45.036 --> 00:10:49.157
"So, don't try to turn these new republics

00:10:49.157 --> 00:10:53.240
"back into colonies under
the rule of monarchies.

00:10:54.217 --> 00:10:55.762
"In fact, just keep your monarchy

00:10:55.762 --> 00:10:59.108
"out of our hemisphere altogether."

00:10:59.108 --> 00:11:03.084
Monroe makes this statement
completely outside

00:11:03.084 --> 00:11:07.124
of the relationship
with the United Kingdom

00:11:07.124 --> 00:11:10.996
so it doesn't have this kind
of riding on the coattails

00:11:10.996 --> 00:11:13.540
feeling of being allied with Britain.

00:11:13.540 --> 00:11:17.099
But nevertheless, the only
way that the United States

00:11:17.099 --> 00:11:21.468
can actually count on the
Monroe Doctrine being enforced

00:11:21.468 --> 00:11:25.635
is because the British Navy
is so incredibly powerful.

00:11:27.333 --> 00:11:30.114
I'm going to draw a very bad boat here.

00:11:30.114 --> 00:11:33.363
Nobody who heard about the
Monroe Doctrine thought,

00:11:33.363 --> 00:11:36.184
"Ah, man, we better not make
the United States angry."

00:11:36.184 --> 00:11:37.204
What they thought was,

00:11:37.204 --> 00:11:40.664
"Ah, man, we better not make
the British Empire angry."

00:11:40.664 --> 00:11:43.501
Because they knew that the British Navy,

00:11:43.501 --> 00:11:45.630
which wanted neutrality of the seas,

00:11:45.630 --> 00:11:47.976
which wanted to be able to continue

00:11:47.976 --> 00:11:49.758
to have these trade relationships

00:11:49.758 --> 00:11:52.058
with new nations in South America,

00:11:52.058 --> 00:11:56.292
would defend the neutrality
and the independence

00:11:56.292 --> 00:11:58.530
of South America by proxy,

00:11:58.530 --> 00:12:02.213
and by doing so, kind of
enforce the Monroe Doctrine.

00:12:02.213 --> 00:12:03.092
So, this is interesting.

00:12:03.092 --> 00:12:05.826
You could think of this as
being a little bit weaselly

00:12:05.826 --> 00:12:10.403
on the part of Monroe,
declaring that the Americas

00:12:10.403 --> 00:12:13.081
should remain free of
the influence of Europe,

00:12:13.081 --> 00:12:17.310
but counting on the United
Kingdom to enforce it.

00:12:17.310 --> 00:12:18.944
Or you could think of it as perhaps

00:12:18.944 --> 00:12:20.803
a brilliant policy maneuver.

00:12:20.803 --> 00:12:21.636
I don't know.

00:12:21.636 --> 00:12:25.862
Certainly, the nations of
South America and Latin America

00:12:25.862 --> 00:12:29.603
appreciated this
declaration of independence

00:12:29.603 --> 00:12:32.585
for the Americas coming
from the United States,

00:12:32.585 --> 00:12:35.860
but they certainly knew
that it was more about

00:12:35.860 --> 00:12:37.774
the United States making sure that

00:12:37.774 --> 00:12:40.696
they, themselves, were
protected than wanting

00:12:40.696 --> 00:12:44.604
to have a real equal
partnership with South America.

00:12:44.604 --> 00:12:48.148
So, the Monroe Doctrine
really didn't amount to much

00:12:48.148 --> 00:12:50.227
for most of the 19th century.

00:12:50.227 --> 00:12:52.908
It was certainly a justification

00:12:52.908 --> 00:12:56.572
as the United States
continued to push west

00:12:56.572 --> 00:12:58.835
in their quest of Manifest Destiny,

00:12:58.835 --> 00:13:00.985
but it will become increasingly important

00:13:00.985 --> 00:13:04.048
in the 20th century as the United States

00:13:04.048 --> 00:13:06.836
steps onto the world
stage with things like

00:13:06.836 --> 00:13:08.919
the Spanish American War,

00:13:11.218 --> 00:13:14.530
under the auspices of William McKinley,

00:13:14.530 --> 00:13:19.436
and making famous Theodore
Roosevelt, saying that

00:13:19.436 --> 00:13:22.687
the Caribbean is the province
of the United States,

00:13:22.687 --> 00:13:25.926
and the nations of Latin
America and South America.

00:13:25.926 --> 00:13:29.547
They're only to be dealt with
through the United States.

00:13:29.547 --> 00:13:31.801
So, you can see the Monroe Doctrine as

00:13:31.801 --> 00:13:35.174
a very early expression
of the United States'

00:13:35.174 --> 00:13:38.045
intention to become a world power

00:13:38.045 --> 00:13:41.966
and to be the leading
and most powerful nation

00:13:41.966 --> 00:13:43.146
in the Americas.

00:13:43.146 --> 00:13:46.404
And you can also see it as an expression

00:13:46.404 --> 00:13:49.012
of American isolationism,

00:13:49.012 --> 00:13:51.164
which will really be

00:13:51.164 --> 00:13:54.914
the leading aspect of
American foreign policy

00:13:56.650 --> 00:13:58.820
up until the Spanish American War.

00:13:58.820 --> 00:14:02.169
As early as George
Washington's Farewell Address,

00:14:02.169 --> 00:14:05.299
Washington expressed the
view that the United States

00:14:05.299 --> 00:14:08.754
should just not get involved
in the business of Europe.

00:14:08.754 --> 00:14:11.357
That that would only lead to heartbreak.

00:14:11.357 --> 00:14:13.850
While the Monroe Doctrine
is now kind of taking

00:14:13.850 --> 00:14:16.759
not only that idea that the United States

00:14:16.759 --> 00:14:19.652
should not become involved
in the affairs of Europe,

00:14:19.652 --> 00:14:22.576
but also turning it around and saying that

00:14:22.576 --> 00:14:24.520
Europe should not become involved

00:14:24.520 --> 00:14:26.743
in the affairs of the Americas,

00:14:26.743 --> 00:14:29.432
drawing an even stronger barrier

00:14:29.432 --> 00:14:31.836
between the old world and the new.


Ordering fractions

WEBVTT
Kind: captions
Language: en

00:00:01.141 --> 00:00:03.567
- [Voiceover] Order the
fractions from least to greatest.

00:00:03.567 --> 00:00:05.065
So we have three fractions,

00:00:05.065 --> 00:00:07.781
and we wanna decide which
one is the smallest,

00:00:07.781 --> 00:00:09.123
which one's in the middle,

00:00:09.123 --> 00:00:11.658
and which is the greatest.

00:00:11.658 --> 00:00:14.400
So one thing we could do
is look at the fractions,

00:00:14.400 --> 00:00:16.963
think about what they
mean, and then estimate.

00:00:16.963 --> 00:00:20.367
7/10, let's say maybe that could represent

00:00:20.367 --> 00:00:23.380
seven of your 10 friends
are wearing blue jeans.

00:00:23.380 --> 00:00:24.407
Well, that's most.

00:00:24.407 --> 00:00:27.462
Most of your friends
are wearing blue jeans,

00:00:27.462 --> 00:00:28.691
and then for 1/3,

00:00:28.691 --> 00:00:31.983
we could say one of your
three teachers wears glasses.

00:00:31.983 --> 00:00:33.061
Well, that's not most.

00:00:33.061 --> 00:00:35.418
If only one of the three wears glasses,

00:00:35.418 --> 00:00:38.269
that's not most of the group.

00:00:38.269 --> 00:00:40.783
So here's a fraction that
represents most of the group.

00:00:40.783 --> 00:00:42.275
Here's one that doesn't.

00:00:42.275 --> 00:00:44.757
So the most is probably greater.

00:00:44.757 --> 00:00:45.874
These two we could compare

00:00:45.874 --> 00:00:48.684
by estimating and see that this one, 7/10,

00:00:48.684 --> 00:00:51.685
is probably greater than 1/3.

00:00:51.685 --> 00:00:53.895
But then we get over here to 5/6,

00:00:53.895 --> 00:00:55.476
and five out of six,

00:00:55.476 --> 00:00:57.699
well, again, that's most of the group,

00:00:57.699 --> 00:00:59.243
but is this most of the group

00:00:59.243 --> 00:01:01.783
greater than the seven
tenths most of the group?

00:01:01.783 --> 00:01:04.616
That gets a lot trickier.

00:01:04.616 --> 00:01:07.582
So what we can do is we can try to change

00:01:07.582 --> 00:01:11.111
these fractions to make
them easier to compare

00:01:11.111 --> 00:01:13.732
so we don't have to
compare 10ths to thirds

00:01:13.732 --> 00:01:15.980
to sixths because those
are all different sizes,

00:01:15.980 --> 00:01:19.011
different sized groups,
different sized pieces,

00:01:19.011 --> 00:01:20.507
that's tricky to compare.

00:01:20.507 --> 00:01:24.137
So we wanna change these
to be the same size.

00:01:24.137 --> 00:01:28.484
So we need some number, a
multiple of 10, three, and six,

00:01:28.484 --> 00:01:32.542
something we can multiply
10, three, and six by

00:01:32.542 --> 00:01:34.214
to get a new denominator

00:01:34.214 --> 00:01:37.547
that will work for all of the fractions.

00:01:38.815 --> 00:01:40.353
One way I like to figure this out

00:01:40.353 --> 00:01:41.917
is I look at the biggest denominator,

00:01:41.917 --> 00:01:43.334
which is 10,

00:01:43.334 --> 00:01:45.372
and I think of its multiples.

00:01:45.372 --> 00:01:49.315
The first multiple is 10,
cause 10 times one is 10.

00:01:49.315 --> 00:01:52.815
Can we change thirds and sixths to have 10

00:01:53.870 --> 00:01:55.277
as a denominator?

00:01:55.277 --> 00:01:57.286
Is there any whole number you can multiply

00:01:57.286 --> 00:01:59.532
three times to get 10?

00:01:59.532 --> 00:02:01.715
There's not, so we need to keep going.

00:02:01.715 --> 00:02:02.835
10 doesn't work.

00:02:02.835 --> 00:02:05.378
The next multiple of 10 is 10 times two,

00:02:05.378 --> 00:02:06.378
which is 20.

00:02:07.990 --> 00:02:10.330
Again, three and six,
is there a whole number

00:02:10.330 --> 00:02:13.337
we can multiply them by to get 20?

00:02:13.337 --> 00:02:15.500
Again, no, so 20 doesn't work.

00:02:15.500 --> 00:02:16.583
How about 30?

00:02:18.988 --> 00:02:20.506
Let's see, three,

00:02:20.506 --> 00:02:22.953
we can multiple three times 10 to get 30,

00:02:22.953 --> 00:02:24.917
so 30 works for three.

00:02:24.917 --> 00:02:26.218
How about six?

00:02:26.218 --> 00:02:28.800
Six times five equals 30, so yes.

00:02:28.800 --> 00:02:31.835
30 can work to be our common denominator.

00:02:31.835 --> 00:02:35.668
30ths, 30 is a multiple
of 10, three, and six.

00:02:38.104 --> 00:02:39.928
So let's start converting our fractions

00:02:39.928 --> 00:02:42.301
to have denominators of 30.

00:02:42.301 --> 00:02:45.408
We'll start with 7/10,

00:02:45.408 --> 00:02:49.281
and we want it to have
a denominator of 30,

00:02:49.281 --> 00:02:51.792
so what do we need to multiply by?

00:02:51.792 --> 00:02:53.542
10 times three is 30.

00:02:54.597 --> 00:02:56.967
We always multiply the
numerator and denominator

00:02:56.967 --> 00:02:59.266
by the same number.

00:02:59.266 --> 00:03:01.516
So seven times three is 21.

00:03:03.416 --> 00:03:06.939
So 7/10 is equal to 21/30.

00:03:06.939 --> 00:03:08.204
These are equal.

00:03:08.204 --> 00:03:10.016
We've just changed the size of the group.

00:03:10.016 --> 00:03:12.947
We've changed the denominator

00:03:12.947 --> 00:03:15.483
so that they will be easier to compare,

00:03:15.483 --> 00:03:18.635
but we've not changed
what portion of the group

00:03:18.635 --> 00:03:20.076
we're representing.

00:03:20.076 --> 00:03:22.404
Seven out of 10 is the same portion

00:03:22.404 --> 00:03:23.737
as 21 out of 30,

00:03:25.219 --> 00:03:29.097
and then let's keep going with 1/3.

00:03:29.097 --> 00:03:31.356
Again, we want a denominator of 30,

00:03:31.356 --> 00:03:34.490
so this time we'll multiply three times 10

00:03:34.490 --> 00:03:35.936
to get 30.

00:03:35.936 --> 00:03:38.059
Again, numerator also times 10.

00:03:38.059 --> 00:03:39.642
One times 10 is 10.

00:03:40.974 --> 00:03:43.929
10 out of 30 is the same as 1/3.

00:03:43.929 --> 00:03:46.923
If you have 10 of the 30 people,

00:03:46.923 --> 00:03:49.059
again, we'll use the wear glasses example,

00:03:49.059 --> 00:03:52.213
or 1/3, that is the
same size of the group,

00:03:52.213 --> 00:03:54.314
the same portion,

00:03:54.314 --> 00:03:58.123
and finally 5/6, what do
we need to multiply here

00:03:58.123 --> 00:03:59.093
to get 30?

00:03:59.093 --> 00:04:01.339
Six times five is 30,

00:04:01.339 --> 00:04:03.603
so we multiply the numerator times five,

00:04:03.603 --> 00:04:05.770
and five times five is 25.

00:04:07.544 --> 00:04:10.888
So now, instead of
these original fractions

00:04:10.888 --> 00:04:13.042
that were tricky to compare,

00:04:13.042 --> 00:04:15.021
we have much easier numbers to compare.

00:04:15.021 --> 00:04:17.104
We have 21/30,

00:04:19.062 --> 00:04:20.479
10/30,

00:04:22.705 --> 00:04:24.455
and 25/30.

00:04:26.614 --> 00:04:28.064
So in this case,

00:04:28.064 --> 00:04:30.422
the pieces are all 30ths.

00:04:30.422 --> 00:04:32.129
They're all groups of 30.

00:04:32.129 --> 00:04:35.351
So this is much easier to compare.

00:04:35.351 --> 00:04:37.754
We can simply look at the numerators

00:04:37.754 --> 00:04:40.894
to see what portion of those 30

00:04:40.894 --> 00:04:42.855
the fraction represents.

00:04:42.855 --> 00:04:47.697
So the first 7/10 is the
same as 21 out of 30,

00:04:47.697 --> 00:04:50.019
whereas 1/3 is 10 out of 30.

00:04:50.019 --> 00:04:53.961
Well, clearly 21 out of
30 is a larger portion

00:04:53.961 --> 00:04:56.090
of the group than 10 out of 30.

00:04:56.090 --> 00:04:58.066
So we were right when we estimated up here

00:04:58.066 --> 00:05:01.659
that 7/10 is larger than 1/3,

00:05:01.659 --> 00:05:03.290
but then the trickier one over here,

00:05:03.290 --> 00:05:04.892
now we can see much more clearly.

00:05:04.892 --> 00:05:08.578
25 out of 30 is the greatest
portion of the group.

00:05:08.578 --> 00:05:11.328
25 is more than the 10 or the 21.

00:05:12.447 --> 00:05:15.538
So we can list these now
from least to greatest.

00:05:15.538 --> 00:05:18.870
The least, the smallest, is 10/30,

00:05:18.870 --> 00:05:22.011
which again, remember, is equal to 1/3.

00:05:22.011 --> 00:05:25.644
So we can put 1/3 is least,

00:05:25.644 --> 00:05:28.076
and we cross that off.

00:05:28.076 --> 00:05:31.243
Next, it's either 21 out of 30, or 25.

00:05:32.226 --> 00:05:36.309
21 is less, and that represented 7/10,

00:05:37.306 --> 00:05:40.030
so we can say 7/10,

00:05:40.030 --> 00:05:43.234
'cause 21/30 equals 7/10,

00:05:43.234 --> 00:05:46.764
and finally that leaves us with 25/30,

00:05:46.764 --> 00:05:49.931
which is equivalent to 5/6.

00:05:51.094 --> 00:05:53.120
So from least to greatest,

00:05:53.120 --> 00:05:56.801
our fractions are 1/3, 7/10,

00:05:56.801 --> 00:05:58.396
and then 5/6.


Complex rotation

WEBVTT
Kind: captions
Language: en

00:00:00.744 --> 00:00:02.069
- [Voiceover] So now, we've seen rotation

00:00:02.069 --> 00:00:04.089
by multiplying j by j,

00:00:04.089 --> 00:00:06.020
over and over again, and we see that

00:00:06.020 --> 00:00:07.469
that's rotation.

00:00:07.469 --> 00:00:10.960
Now, let's do it for the general
idea of any complex number.

00:00:10.960 --> 00:00:13.149
So, if I have a complex number,

00:00:13.149 --> 00:00:15.988
we'll call it z, and we'll
say it's made of two parts.

00:00:15.988 --> 00:00:20.155
A real part called a, and
an imaginary part called b.

00:00:21.279 --> 00:00:22.491
So now, what I want to do is,

00:00:22.491 --> 00:00:26.769
what happens if we
multiply z by j one time?

00:00:26.769 --> 00:00:27.602
J times z.

00:00:29.097 --> 00:00:31.097
And that equals, j times

00:00:33.228 --> 00:00:34.095
a plus

00:00:34.095 --> 00:00:35.632
jb.

00:00:35.632 --> 00:00:38.334
And let's just multiply it through.

00:00:38.334 --> 00:00:39.667
Equals j times a

00:00:41.185 --> 00:00:42.185
plus j times

00:00:44.166 --> 00:00:44.999
j times b.

00:00:48.933 --> 00:00:50.580
A and b have now switched places.

00:00:50.580 --> 00:00:53.437
So, we're gonna put ja on this side,

00:00:53.437 --> 00:00:55.273
ja on this side.

00:00:55.273 --> 00:00:56.602
And what do we have here?

00:00:56.602 --> 00:01:00.102
J times j is minus one, so we have minus b

00:01:02.002 --> 00:01:02.835
plus ja.

00:01:10.782 --> 00:01:13.606
So, now we have expressions for z and jz.

00:01:13.606 --> 00:01:16.503
And I wanna plot these on a complex plane

00:01:16.503 --> 00:01:18.836
and see what they look like.

00:01:20.611 --> 00:01:23.945
And here's the real axis,
here's the imaginary axis.

00:01:23.945 --> 00:01:25.695
And let's first plot,

00:01:27.782 --> 00:01:32.021
let's plot z, let's say
z has a large real value,

00:01:32.021 --> 00:01:34.027
and that would be a.

00:01:34.027 --> 00:01:38.194
And let's say that b is a
smaller value, we'll put b here.

00:01:39.971 --> 00:01:42.097
And that means that z is at a location

00:01:42.097 --> 00:01:44.930
in the complex plane, right there.

00:01:47.884 --> 00:01:50.301
We can plot the dotted lines.

00:01:55.672 --> 00:01:58.462
That's z in the complex plane.

00:01:58.462 --> 00:02:00.560
So now, let's put jz on this same plot.

00:02:00.560 --> 00:02:04.100
Jz has a real component of minus b,

00:02:04.100 --> 00:02:07.354
so that would be right about here.

00:02:07.354 --> 00:02:08.521
Here's minus b

00:02:09.364 --> 00:02:10.629
and it has a

00:02:10.629 --> 00:02:13.137
imaginary component of plus a.

00:02:13.137 --> 00:02:14.701
So, let's swing a,

00:02:14.701 --> 00:02:17.701
a goes all the way up to about here.

00:02:18.761 --> 00:02:21.261
And so, that's the location of

00:02:25.007 --> 00:02:25.840
jz.

00:02:29.429 --> 00:02:31.227
And let me draw the hypotenuse of that.

00:02:31.227 --> 00:02:35.802
This is the vector
representing jz, right there.

00:02:35.802 --> 00:02:37.954
So, now we have a bunch
of triangles on the page,

00:02:37.954 --> 00:02:39.756
and what I wanna demonstrate is that

00:02:39.756 --> 00:02:42.756
this angle right here is 90 degrees.

00:02:45.743 --> 00:02:46.919
So, one way to do that,

00:02:46.919 --> 00:02:48.279
let's see if we can do that.

00:02:48.279 --> 00:02:51.895
Let's say this angle here is theta.

00:02:51.895 --> 00:02:54.920
That's the angle right there.

00:02:54.920 --> 00:02:58.874
Now, this triangle here, this
triangle that we sketched in,

00:02:58.874 --> 00:03:01.140
just imagine in your head
that we're gonna rotate

00:03:01.140 --> 00:03:05.317
that angle up until the
a leg of that triangle

00:03:05.317 --> 00:03:08.290
is resting right here
on the imaginary axis.

00:03:08.290 --> 00:03:12.457
So, this triangle rotates up
to become this triangle here.

00:03:14.545 --> 00:03:18.761
Since we moved that triangle,
we know that this angle here,

00:03:18.761 --> 00:03:20.261
that's also theta.

00:03:21.156 --> 00:03:23.991
It's the same triangle, just rotated up.

00:03:23.991 --> 00:03:25.917
And what does that make this angle here?

00:03:25.917 --> 00:03:27.167
This angle here

00:03:29.505 --> 00:03:30.422
that equals

00:03:31.650 --> 00:03:32.483
90 degrees

00:03:33.523 --> 00:03:34.523
minus theta.

00:03:38.788 --> 00:03:42.678
So, if I combine this theta
angle with this angle here,

00:03:42.678 --> 00:03:44.537
what do I get?

00:03:44.537 --> 00:03:45.370
Theta plus

00:03:47.426 --> 00:03:49.259
90 degrees minus theta

00:03:50.458 --> 00:03:52.291
and we get 90 degrees.

00:03:53.882 --> 00:03:55.734
So, we just showed that
this angle right here

00:03:55.734 --> 00:03:57.992
is a 90 degree angle.

00:03:57.992 --> 00:04:00.603
That demonstrates that
any complex number z,

00:04:00.603 --> 00:04:02.489
if I multiply it by j,

00:04:02.489 --> 00:04:06.656
that results in a positive
rotation of 90 degrees.

00:04:08.090 --> 00:04:10.198
So, let's do this rotation
again, only this time,

00:04:10.198 --> 00:04:13.515
instead of using the
rectangular coordinate system,

00:04:13.515 --> 00:04:16.722
let's use the exponential representation.

00:04:16.722 --> 00:04:18.874
So, in the exponential notation, we say,

00:04:18.874 --> 00:04:21.541
in general, z equals some radius

00:04:22.696 --> 00:04:24.613
times e to the j theta.

00:04:25.999 --> 00:04:27.865
Or this is the angle theta

00:04:27.865 --> 00:04:30.394
and r is the length of
this hypotenuse here

00:04:30.394 --> 00:04:31.727
to get out to z.

00:04:32.859 --> 00:04:36.276
So, what is in this notation, what is jz?

00:04:38.130 --> 00:04:39.380
And that equals

00:04:41.405 --> 00:04:42.238
j times r

00:04:43.901 --> 00:04:45.318
e to the j theta.

00:04:47.426 --> 00:04:49.239
So, now I'm gonna do a little trick,

00:04:49.239 --> 00:04:53.059
where I'm gonna represent
j in exponential notation.

00:04:53.059 --> 00:04:55.392
So, if I color in dark here,

00:04:56.826 --> 00:04:57.659
this is j.

00:04:58.945 --> 00:05:02.860
The vector j is right there
and it has a magnitude of one

00:05:02.860 --> 00:05:05.914
and it points straight
up on the imaginary axis.

00:05:05.914 --> 00:05:08.066
So, I can represent j, like this.

00:05:08.066 --> 00:05:09.399
I can say j is e

00:05:10.490 --> 00:05:11.323
to the j

00:05:12.470 --> 00:05:13.387
90 degrees.

00:05:15.249 --> 00:05:18.650
That's equivalent to this j here

00:05:18.650 --> 00:05:20.650
and it's multiplied by r

00:05:22.004 --> 00:05:22.837
e to the j

00:05:24.023 --> 00:05:24.856
theta.

00:05:27.139 --> 00:05:28.191
And now the last step is

00:05:28.191 --> 00:05:33.058
we just combine these two
exponents together and we get

00:05:33.058 --> 00:05:33.891
jz

00:05:35.538 --> 00:05:37.199
equals r

00:05:37.199 --> 00:05:38.032
times e

00:05:39.030 --> 00:05:39.863
to the j

00:05:42.645 --> 00:05:43.478
theta plus

00:05:46.168 --> 00:05:47.085
90 degrees.

00:05:49.984 --> 00:05:54.020
So, in exponential notation,
we get this vector here.

00:05:54.020 --> 00:05:57.415
We go an additional 90 degree rotation

00:05:57.415 --> 00:06:01.582
and we go out the same
distance we had originally, r.

00:06:02.604 --> 00:06:05.812
So, now we've shown that we we
can rotate any complex number

00:06:05.812 --> 00:06:09.356
by 90 degrees if we multiply it by j.

00:06:09.356 --> 00:06:11.997
We're gonna get to apply this
kind of transformation to

00:06:11.997 --> 00:06:14.937
working out the current and
voltage relationships in

00:06:14.937 --> 00:06:16.880
inductors and capacitors,

00:06:16.880 --> 00:06:19.503
and that'll happen in a
couple videos from now.


Diode graphical solution

WEBVTT
Kind: captions
Language: en

00:00:01.810 --> 00:00:04.344
- [Voiceover] Now I wanna
use a diode in a circuit,

00:00:04.344 --> 00:00:07.501
and we'll see how we solve
circuits that include

00:00:07.501 --> 00:00:09.954
these nonlinear diodes in them.

00:00:09.954 --> 00:00:12.875
So I have a circuit here
with a battery and a resistor

00:00:12.875 --> 00:00:15.392
and a diode here, and it's
gonna be a special kind,

00:00:15.392 --> 00:00:17.110
it's gonna be an LED diode,

00:00:17.110 --> 00:00:19.097
so it's gonna give off light.

00:00:19.097 --> 00:00:22.274
This is a kind of diode that's
manufactured to generate

00:00:22.274 --> 00:00:25.867
photons of light when it has
a current flowing through it

00:00:25.867 --> 00:00:27.721
in the forward direction.

00:00:27.721 --> 00:00:29.961
They're pretty cool and
you see them all the time

00:00:29.961 --> 00:00:31.887
in electronic components.

00:00:31.887 --> 00:00:34.235
So we're gonna figure
out how to use an LED

00:00:34.235 --> 00:00:36.902
in a real simple little circuit.

00:00:38.694 --> 00:00:41.142
And in our circuit here,
we're gonna have a resistor

00:00:41.142 --> 00:00:42.142
of 330 ohms,

00:00:44.367 --> 00:00:48.455
and we'll make this battery three volts,

00:00:48.455 --> 00:00:51.122
so it's like two double-A cells.

00:00:54.307 --> 00:00:55.845
And what we wanna find out is

00:00:55.845 --> 00:00:58.611
how much current's gonna
flow around this circuit.

00:00:58.611 --> 00:01:00.981
And then we label this here,

00:01:00.981 --> 00:01:04.326
let me label the voltages
across our components.

00:01:04.326 --> 00:01:07.826
We'll have VD, which is this voltage here,

00:01:09.676 --> 00:01:13.640
and we'll have VR, which
is the resistor voltage,

00:01:13.640 --> 00:01:16.827
and that's that voltage right there.

00:01:16.827 --> 00:01:20.895
So now I'm gonna show you
a plot of the iv curve

00:01:20.895 --> 00:01:22.181
of our diode.

00:01:22.181 --> 00:01:24.147
You can see right here, around 0.7 volts,

00:01:24.147 --> 00:01:27.811
the current rises rapidly
when there's 0.7 volts

00:01:27.811 --> 00:01:29.228
across the diode.

00:01:30.325 --> 00:01:32.557
And let's start out by analyzing this,

00:01:32.557 --> 00:01:35.191
let's start with the same
tools that we always have,

00:01:35.191 --> 00:01:38.272
which is, let's try to
write some current laws

00:01:38.272 --> 00:01:39.974
for these two things.

00:01:39.974 --> 00:01:42.135
So for the diode, we write a current law

00:01:42.135 --> 00:01:43.931
that looks like this.

00:01:43.931 --> 00:01:46.598
The current is equal to IS times

00:01:48.111 --> 00:01:49.028
e to the qv

00:01:50.823 --> 00:01:51.656
on kT

00:01:53.579 --> 00:01:54.877
minus one.

00:01:54.877 --> 00:01:57.595
So that's the iv
characteristic for the diode,

00:01:57.595 --> 00:01:59.345
where this is V diode

00:02:01.950 --> 00:02:06.806
right there, and the corresponding
equation for the resistor

00:02:06.806 --> 00:02:08.639
is i equals V resistor

00:02:10.996 --> 00:02:11.829
over 330

00:02:14.939 --> 00:02:15.772
ohms.

00:02:16.925 --> 00:02:19.139
That's just Ohm's Law for the resistor,

00:02:19.139 --> 00:02:22.556
and i in both cases is this i right here.

00:02:24.524 --> 00:02:27.018
Now if I wanted to, I could
set these two expressions

00:02:27.018 --> 00:02:31.185
equal to each other and
solve somehow for VD and VR,

00:02:32.055 --> 00:02:33.847
but what we're gonna do instead
is we're gonna solve this

00:02:33.847 --> 00:02:36.956
by graphing, by a graphical method.

00:02:36.956 --> 00:02:39.064
Here's a graph for the diode,

00:02:39.064 --> 00:02:42.166
and this is the VD scale, this is V diode,

00:02:42.166 --> 00:02:43.999
and this is i up here.

00:02:45.041 --> 00:02:47.318
And so what I wanna do is I
wanna plot the resistor curve

00:02:47.318 --> 00:02:48.267
around here as well.

00:02:48.267 --> 00:02:50.864
I wanna plot the resistor iv curve

00:02:50.864 --> 00:02:52.843
on this same plot.

00:02:52.843 --> 00:02:56.533
Now, in this expression,
I have VR instead of VD,

00:02:56.533 --> 00:02:59.783
so let me see if I can work on VR here.

00:03:04.685 --> 00:03:08.136
Let me try to figure
out VR in terms of VD.

00:03:08.136 --> 00:03:09.636
So I can derive VR

00:03:10.590 --> 00:03:11.757
as three volts

00:03:13.428 --> 00:03:14.261
minus VD.

00:03:20.299 --> 00:03:22.566
And let's put this into
this i expression here.

00:03:22.566 --> 00:03:25.272
The Ohm's Law expression now becomes

00:03:25.272 --> 00:03:26.105
i equals,

00:03:27.912 --> 00:03:30.829
VR is replaced with three minus VD,

00:03:33.810 --> 00:03:35.310
all over 330 ohms.

00:03:38.478 --> 00:03:40.906
And let's work on this a little more.

00:03:40.906 --> 00:03:41.739
i equals

00:03:45.233 --> 00:03:46.400
three over 330

00:03:48.661 --> 00:03:50.161
minus VD over 330,

00:03:55.092 --> 00:03:59.344
and this is starting to look
like the equation of a line.

00:03:59.344 --> 00:04:03.511
Let me write this to recognize
it as a equation of a line.

00:04:05.004 --> 00:04:05.837
Minus VD

00:04:08.572 --> 00:04:09.405
over 330

00:04:14.604 --> 00:04:17.771
plus three over 330 is nine milliamps.

00:04:23.903 --> 00:04:26.314
So this is the equation
of a line, and the slope

00:04:26.314 --> 00:04:29.397
is right here, is minus one over 330,

00:04:30.932 --> 00:04:34.099
and the i-intercept is nine milliamps.

00:04:35.793 --> 00:04:37.521
So let's see if we can plot this line.

00:04:37.521 --> 00:04:40.435
This is actually called a

00:04:40.435 --> 00:04:41.268
Load Line.

00:04:44.183 --> 00:04:47.227
That's just a nickname for
this kind of expression

00:04:47.227 --> 00:04:50.615
that you get when you
have a resistor connected

00:04:50.615 --> 00:04:53.770
to a fixed power supply
above and the resistor is

00:04:53.770 --> 00:04:55.520
hanging down from it.

00:04:56.620 --> 00:04:59.234
You get this characteristic
equation of a line

00:04:59.234 --> 00:05:03.718
that has a negative slope,
which is really distinctive.

00:05:03.718 --> 00:05:05.577
Let's see if we can plot this line.

00:05:05.577 --> 00:05:08.619
Now, it's a line, so all we
have to do is find two points

00:05:08.619 --> 00:05:12.261
that solve the line and then
we'll be able to draw the line.

00:05:12.261 --> 00:05:14.785
So if I set VD equal to zero,

00:05:14.785 --> 00:05:17.202
then i equals nine milliamps.

00:05:18.427 --> 00:05:22.195
So here's VD equal to
zero, and it'll go through

00:05:22.195 --> 00:05:23.951
nine milliamps.

00:05:23.951 --> 00:05:24.784
So that's

00:05:25.796 --> 00:05:27.629
one point on the line.

00:05:29.085 --> 00:05:30.255
But what else can I set to zero?

00:05:30.255 --> 00:05:31.931
I can set i equal to zero,

00:05:31.931 --> 00:05:34.931
which means I'm on the voltage axis.

00:05:35.935 --> 00:05:37.576
And what I'm actually gonna do

00:05:37.576 --> 00:05:39.674
is I'm just gonna look at my
circuit and figure this out

00:05:39.674 --> 00:05:41.174
in my head.

00:05:41.174 --> 00:05:43.957
So I'm setting i equal to zero,

00:05:43.957 --> 00:05:47.225
and i equal zero means there's
no current in this resistor,

00:05:47.225 --> 00:05:50.689
which means there's no voltage
drop across that resistor.

00:05:50.689 --> 00:05:53.626
And that means that this voltage here

00:05:53.626 --> 00:05:56.659
is the same as this voltage here.

00:05:56.659 --> 00:05:57.960
And I know the voltage here,

00:05:57.960 --> 00:06:00.847
the voltage here is three volts,

00:06:00.847 --> 00:06:04.101
so that means the voltage
here is three volts,

00:06:04.101 --> 00:06:08.254
and that's because I
know the current is zero.

00:06:08.254 --> 00:06:11.372
So let's go over and put
that point on a line.

00:06:11.372 --> 00:06:14.372
So when i is zero, v is three volts.

00:06:15.344 --> 00:06:18.863
So there's another point on the line.

00:06:18.863 --> 00:06:20.784
And now we have two points
and we can draw a line

00:06:20.784 --> 00:06:21.784
between 'em,

00:06:22.984 --> 00:06:23.817
like that.

00:06:28.134 --> 00:06:31.462
And what we've drawn is the Load Line

00:06:31.462 --> 00:06:33.629
for this 330-ohm resistor.

00:06:35.522 --> 00:06:37.527
You remember, back over
here we said we could solve

00:06:37.527 --> 00:06:39.669
these two equations by setting the two is

00:06:39.669 --> 00:06:41.190
equal to each other,

00:06:41.190 --> 00:06:44.332
and that's basically where
do these two lines intersect?

00:06:44.332 --> 00:06:46.832
And they intersect right here.

00:06:47.919 --> 00:06:50.836
That's the solution to our problem.

00:06:52.171 --> 00:06:54.220
So this intersection
point is the solution.

00:06:54.220 --> 00:06:56.812
It's where the resistor
current and the diode current

00:06:56.812 --> 00:06:59.428
are the same, and that's that point there.

00:06:59.428 --> 00:07:02.261
Now I can just read off my answer.

00:07:04.190 --> 00:07:06.773
Right there is about 0.7 volts,

00:07:09.088 --> 00:07:13.255
and the current over here,
if I read off the current,

00:07:14.919 --> 00:07:18.421
just straight across there, it's about

00:07:18.421 --> 00:07:19.254
6.8

00:07:21.397 --> 00:07:23.147
milliamps of current.

00:07:24.289 --> 00:07:27.789
So now we actually just solved our circuit

00:07:29.692 --> 00:07:32.482
using a graphical technique.

00:07:32.482 --> 00:07:34.978
And what that says is,

00:07:34.978 --> 00:07:38.793
let me erase this a bit to clean it up.

00:07:38.793 --> 00:07:42.386
Let me take out these two things here.

00:07:42.386 --> 00:07:44.636
That was just the resistor Load Line

00:07:44.636 --> 00:07:47.484
that we were talking about.

00:07:47.484 --> 00:07:51.309
And now for our solution, we have i equals

00:07:51.309 --> 00:07:52.476
6.8 milliamps,

00:07:54.539 --> 00:07:55.372
and V,

00:07:57.973 --> 00:08:00.556
V diode equals about 0.7 volts.

00:08:04.049 --> 00:08:06.709
So that's how you do a
graphical solution with a diode.


Ecological succession

WEBVTT
Kind: captions
Language: en

00:00:00.000 --> 00:00:01.041
- [Voiceover] You look at a community

00:00:01.041 --> 00:00:04.389
that is in a given habitat,
a natural question is to say,

00:00:04.389 --> 00:00:06.991
well, has that community
always been that way?

00:00:06.991 --> 00:00:08.225
Has it always been there?

00:00:08.225 --> 00:00:11.017
Was there a time where maybe
there was no life there?

00:00:11.017 --> 00:00:14.244
And the answer is, well, yes,

00:00:14.244 --> 00:00:16.498
the communities do change over time,

00:00:16.498 --> 00:00:18.542
and there is some initial period

00:00:18.542 --> 00:00:22.085
where there might not be
any life in that habitat,

00:00:22.085 --> 00:00:24.848
and then life slowly colonizes it,

00:00:24.848 --> 00:00:27.903
and the makeup of that
life will change over time,

00:00:27.903 --> 00:00:29.550
the makeup of that community.

00:00:29.550 --> 00:00:33.468
And this general idea is
called ecological succession.

00:00:33.468 --> 00:00:35.301
Ecological succession.

00:00:37.533 --> 00:00:39.444
And folks will often talk about

00:00:39.444 --> 00:00:42.254
the different types of
ecological succession,

00:00:42.254 --> 00:00:46.244
splitting it up into primary
ecological succession,

00:00:46.244 --> 00:00:50.077
and so primary is when
you start with no life,

00:00:51.690 --> 00:00:54.258
because you really have a new habitat,

00:00:54.258 --> 00:00:56.697
and then slowly life colonizes it.

00:00:56.697 --> 00:00:58.088
And the best example of that,

00:00:58.088 --> 00:00:59.426
or one of the best examples of that

00:00:59.426 --> 00:01:01.556
is when new land forms due to lava flows.

00:01:01.556 --> 00:01:03.170
There are pictures from Hawaii,

00:01:03.170 --> 00:01:06.833
where new land is forming
as this lava hardens.

00:01:06.833 --> 00:01:09.956
And, at first, there is,
when it's molten lava,

00:01:09.956 --> 00:01:11.638
there's no life there, then it hardens,

00:01:11.638 --> 00:01:15.074
and slowly, basic life,
or life in general,

00:01:15.074 --> 00:01:18.241
will start to colonize that lava rock.

00:01:19.291 --> 00:01:21.984
And some of it you won't be
able to see with your naked eye,

00:01:21.984 --> 00:01:23.473
it would be microbes,

00:01:23.473 --> 00:01:24.643
and some of it you could see,

00:01:24.643 --> 00:01:27.873
it could be simple ferns
and plants like that,

00:01:27.873 --> 00:01:30.511
and these are often called
the pioneer species.

00:01:30.511 --> 00:01:32.706
But what they often do
is make that environment

00:01:32.706 --> 00:01:35.552
more suitable for other types of life.

00:01:35.552 --> 00:01:38.146
So they might slowly break down that rock.

00:01:38.146 --> 00:01:40.999
As they die, along with
the broken down rock

00:01:40.999 --> 00:01:42.894
that also gets eroded from the water

00:01:42.894 --> 00:01:44.971
and the air and the rain,

00:01:44.971 --> 00:01:48.696
it starts to make soil and
conditions more suitable

00:01:48.696 --> 00:01:51.589
for other types of species.

00:01:51.589 --> 00:01:52.765
And these pioneer species,

00:01:52.765 --> 00:01:55.116
they don't even have to
just be plants and microbes.

00:01:55.116 --> 00:01:58.109
I was just reading an
article about how in Hawaii,

00:01:58.109 --> 00:02:00.217
humans want to get that land

00:02:00.217 --> 00:02:03.006
because it's beachfront property.

00:02:03.006 --> 00:02:05.803
Or the beach might not
have formally formed

00:02:05.803 --> 00:02:08.987
in the traditional sense, but
you have ocean view property.

00:02:08.987 --> 00:02:11.351
So humans might be some of
the first pioneer species

00:02:11.351 --> 00:02:14.182
who might wanna be out on that land.

00:02:14.182 --> 00:02:17.912
And that new land doesn't
just form from lava flows.

00:02:17.912 --> 00:02:21.957
There are other examples
of new habitats forming.

00:02:21.957 --> 00:02:26.124
So right here, we have pictures
of a new habitat forming

00:02:28.355 --> 00:02:31.289
because of the retreat of glaciers.

00:02:31.289 --> 00:02:33.173
When the glaciers were
covering up these rocks,

00:02:33.173 --> 00:02:34.562
you didn't have life on them.

00:02:34.562 --> 00:02:38.335
But as the glacier
retreats right over here,

00:02:38.335 --> 00:02:40.424
you see things like these mosses

00:02:40.424 --> 00:02:44.260
and other types of pioneer
species starting to colonize.

00:02:44.260 --> 00:02:45.950
And over time, they're going to make it

00:02:45.950 --> 00:02:48.988
more and more suitable for
other types of species.

00:02:48.988 --> 00:02:50.947
So that's primary succession.

00:02:50.947 --> 00:02:53.980
Another situation is when you
have secondary succession.

00:02:53.980 --> 00:02:55.360
And there's many different ways

00:02:55.360 --> 00:02:57.734
you could have secondary succession.

00:02:57.734 --> 00:03:00.234
One of the most cited examples

00:03:02.147 --> 00:03:06.107
is when you have some type of a disaster.

00:03:06.107 --> 00:03:09.535
And so this right over here,
this is a picture of a fire,

00:03:09.535 --> 00:03:13.702
so here, we're talking
'bout secondary succession,

00:03:15.131 --> 00:03:17.841
where you had a community,
but then you have a fire,

00:03:17.841 --> 00:03:20.417
and so that fire might wipe
out a lot of the community.

00:03:20.417 --> 00:03:24.120
And then it creates space
for other things to form.

00:03:24.120 --> 00:03:25.504
So after you have a fire,

00:03:25.504 --> 00:03:27.504
the forest might look something like this,

00:03:27.504 --> 00:03:31.730
and then, notice, you have
species that start to colonize

00:03:31.730 --> 00:03:34.168
where a lot of other
species might have died

00:03:34.168 --> 00:03:36.109
or died during the fire.

00:03:36.109 --> 00:03:40.109
And sometimes, after this
disaster of some kind,

00:03:41.295 --> 00:03:45.236
you might get back to the
same type of community

00:03:45.236 --> 00:03:46.870
that you had before the disaster,

00:03:46.870 --> 00:03:48.989
but sometimes, it could be
a completely different one,

00:03:48.989 --> 00:03:52.072
that the communities don't come about

00:03:53.266 --> 00:03:55.712
in exactly the same way.

00:03:55.712 --> 00:03:59.109
So the general idea is
communities change over time,

00:03:59.109 --> 00:04:00.986
we have ecological succession.

00:04:00.986 --> 00:04:02.474
There are times where
there's no community,

00:04:02.474 --> 00:04:04.862
and then they come in,
that's primary succession.

00:04:04.862 --> 00:04:06.554
And then, you have times where you have

00:04:06.554 --> 00:04:07.895
disasters of some kind

00:04:07.895 --> 00:04:10.159
that could change the
environment in some ways,

00:04:10.159 --> 00:04:12.477
and it could change the
makeup of that community.

00:04:12.477 --> 00:04:14.088
And things don't have to be as dramatic

00:04:14.088 --> 00:04:16.823
as new land formation because of lava

00:04:16.823 --> 00:04:20.947
or because of forest fires
or even glaciers retreating.

00:04:20.947 --> 00:04:22.772
It could because of a disease,

00:04:22.772 --> 00:04:24.474
or it could just be because

00:04:24.474 --> 00:04:27.557
a new species gets introduced somehow

00:04:28.579 --> 00:04:31.367
that changes the makeup,
changes the competition,

00:04:31.367 --> 00:04:34.884
the predatory, the various,
the symbiotic dynamics

00:04:34.884 --> 00:04:36.801
within that community.