Show your parents the data that class size has nothing to do with the quality of the education (unless you get down to about 12 students or so), and then ask them what the real reason is that they want you to go to this school. Tell them that to have a productive dialog, both sides have to lay their cards face up on the table. After your parents recover from their shock, and ask who is "coaching you" (you can tell them your lawyer is
), maybe you will make more progress. Are you getting good grades? Also tell them you want to set up an appointment with the principal of the public school for them. Get the principal of the charter school to tell your parents that it is a mistake to make you stay there against your will. Talk to the principal of the charter school yourself to make your case, and explain your reasons, and get him or her on your side. (The too much work thing worries me; there is never too much work! You aren't trying to just laze out are you?)
By the way, my parents let me choose my schools. Whatever I wanted was OK. In high school, I got my Dad to write out about 30 excuse slips at once for my first class (a biology class), because I told him that the teacher knew only about 50% of what was in the dumbed down textbook, and I was getting bored with correcting his errors in class, and I thought it best for both myself and my teacher that I make myself more relatively scarce. The bio teacher at one point asked if I were having medical problems, and I said yes, of a psychological kind, and was in therapy.