Stand and Deliver (1988). The story of Jaime Escalante, a high school teacher who successfully inspired his dropout prone students to learn calculus.
This is a great film, and definitely one of the better teacher-makes-a-difference ones. It’s a shame it came out only a year before Dead Poets Society which may be the best of the subgenre. That said, there’s a beauty in this one that takes it beyond the trope, a loving underdog narrative well told. It’s pretty damn good. 8/10.