What evidence supports this claim: Dr.suggests that teachers should teach the Growth Mindset in their classrooms?

Teachers who use Growth Mindset are nicer teachers who don't assign a lot of classwork or homework.
Over time, the students using a Growth Mindset raised their grades because they tried harder on assignments.
Students who feel discouraged about tough questions are just lazy and should try harder in school.
Students who have a Growth Mindset saw their grades drop because they avoided hard assignments.