Inquiring, inquisitive, curious, eager to learn, aware of things that aren't always readily explained. Stuff like that. You should never stifle a person who wants to know something. That can turn them off to learning, and that isn't a good thing. I very strongly encourage my daughter to go ahead and ask the questions, and if I don't know, then I will help her to find out. As they saying goes, a mind is a terrible thing to waste.
Inquisitive, bored or this may be just needing human contact, someone just needing a friend or someone who just is not up to date on a lot of things, or a kid who is just bored to death and enjoys asking dumb questions.
A questioner or interviewer.some people just like doing that.
I am one of them and I am a curious person.
Thats just it you don't call them, nothing but nosey.