A lot of times, teachers can't think creatively, or they don't have enough knowledge beyond the syllabus, and when you try to think or you ask them beyond the books, very few have the capabilities to back there answer with sufficient knowledge, they know if they answer one question tomorrow they will have 5 more to answer and so on....only the ones who know properly will encourage you to ask....

I have noticed, teachers who know are cool about you experimenting around, but teachers who don't know will get irritated very soon.... i always ask 2-3 questions when i meet a new teacher, things off the syllabus to see how they ans, wether they give right ans, wrong ans just coz they have to, they don't give, or answer later (some actually did).... when i know who knows how much, i attend and ask accoridingly...