Well, I'm 14, I live in a small town (not that big) in Brazil and at the moment I'm only out to my best friend, he was really supportive when I came out to him. Well, I have 3 gay cousins in my family (2 men and a woman) they are not out yet, but I 100% sure that they are gay, relatives heard about it too. My mom is quite homophobic, she usually says that "It must be really disappointing for a Mom to know that her child is gay". Someday I'll tell her, I have been thinking about doing it after college, when I want to move to the USA, but that'll be in 11/12 years. If I tell her that I'm gay, I would be OK if everybody knew about it. I have been thinking about making a question about what would you do if your son/daughter was gay, something like that, I would tell her that it was a school homework and if she answer to it in a positive way, I would came out to her. Is it a good idea ? Sorry if I wrote/spelled anything wrong.
I like the idea of you coming out through her answer to another question that can be related to your education However, when you ask the question, don't seem to eager to proceed with another statement because how you ask it may or may not raise suspicion of the real motive behind asking the question. When you want to tell her is up to you, if you strongly believe she'll respond very negatively, then I'd wait until you're on your own. Best of luck!!