You should first let the teacher know in private that you do not like it and ask them nicely to stop. Hopefully, at that point they will apologize and stop doing it. If they do not stop after that you should complain to the principal and your parents.
Anyone can use alchemy as it is not that different from chemistry. But like chemistry it has hazards so you should use caution, acquire knowledge, have emergency numbers for things such as poison control, and safety equipment. It can be performed with many instruments used in chemistry.