I have a crush on my teacher. Normally when I have a crush I can get over it, but he’s so nice to me, and thinks of me as a friend. Should I tell him?

Depends entirely on situation.

1. Teachers usually are cordial to all.You have to differentiate that he is incline towards you.
2. I hope you are a teenager.In the teachers age, they are NOT very keen in hook ups.They want more stable relationship.
3. You have to tell him for relationship to start.You have the privilege.You can be excused as a small teenager if he says no.
4. Its better to tell him at appropriate time rather to wait till infinity.Whatever will be his answer, he will never break his student-teacher relation with you and your heart will also get cleared.According to “Zeigarnik effect” unfinished tasks always occupy our mind.Finish it, even in case of a heartbreak, you can focus on other jobs.
5. Don’t worry of consequences. At most he will counsel you as a child.You can propose his as if you are having a problem and seek a solution.

https://hemantpandeyblog820899289.wordpress.com/2017/08/18/hemant-pandeys-answer-to-what-are-the-psychological-facts-about-crush-or-falling-in-love-that-people-dont-know-quora-2/