 And they praised one group for how smart they were and they praised the other group for how hard they worked. They then gave the same group of kids another math test with most of the same problems, a few that were harder. The kids who were praised for how smart they were did significantly worse on the second test versus the kids who were praised for their effort. Why? Well, effort is within my control. And if I'm praised for effort, the harder I work, the more praise I'll get. So I'm motivated by this.