Fist Fight (2017) on Netflix

Plot summary

Roosevelt High is down to its last day before summer, and the senior class has turned it into a prank day. English teacher Andy Campbell, whose wife Maggie is pregnant, is waiting on an evaluation that could cost him his job. History teacher Ron Strickland, the one the students fear most, is showing a video when a student named Neil secretly uses his phone to shut it off; Strickland destroys the phone with a swing against the board, and when Neil repeats the trick, he comes back with a fire ax for Neil's desk. Principal Tyler calls both men in and says he will fire them unless one of them speaks. Campbell names Strickland, who loses his job and challenges Campbell to a fight after school. Holly and Coach Crawford expect Strickland to finish him with one punch.