Mojo is a monster with a problem. He used to like school, but then math got hard, and Mojo decided he was not smart enough. School became less fun, and Mojo wanted to make a run for it. But he didn’t, because Mojo was designed by Class Dojo, a Silicon Valley edtech start up, and a team of researchers from Stanford University to teach kids things like the importance of a “growth mindset” (the belief…