Why don't most teachers at public schools let us think for ourselves? it's insulting. I am in English 3 and my teacher does all our work for us.

What should we do?

Here is my advice. Either bite your lip, and remain quiet, or discuss it privately with the teacher. Be respectful. In the end, you may have to bite your lip anyway.
Over a period of several courses, it works out even: some will have you do more than your share of work.
Good luck.