How about I refuse to stop talking in my room when my sister is studying?
Are you interrupting her?
I don't want to study that useless stuff. And I refuse to stop talking because I'm doing something important!
If it isn't something urgent, I don't think being a bit more quiet is too much to ask. Especially if she can hear you from your room.
She's just jealous of me because I'm better than her. I make better grades than her.
A lot of people would call you childish for refusing to stop talking while she is attempting to study. Just because you're better at tests, doesn't mean that you are a better person and you are proving it every time you refuse to take your conversations elsewhere when your sister is trying to better herself.