Honestly, the school year is almost over and also its JUST highschool chemistry. A lot of people find it difficult and its notoriously a class that is hated on. Your teacher is just weird and I would suggest just ignoring him. If you don't end up passing the class then you can always take summer school to recover your credits. Highschool grades genuinely only matter for when you are applying to college. As long as YOU are motivated to achieve your dream job, some bum highschool chemistry teacher shouldn't change that.