In the Netherlands we don't have this kind of thing. I don't know at what age you have a science fair? At age 4-12 you don't really have stuff you don't really have homework, except if you're lagging behind with your work. So all activities will be done at the school, sometimes they ask a parent to help with extracurricular activities. We don't really have a science fair. Closest thing would be a "spreekbeurt" which would translate as oral presentation. You pick a topic you like and explain what it's about. I think many parents help with the preparation for that. But you would have trouble answering the questions if your parents did everything.

At age 12-17 you get more beta courses, chemistry, physics, geography. You can pick a track that best suits your interests/aptitude. They focus on economics, social studies and art, nature and health or nature and technology. You get advanced courses that fit that track and more entry level courses for the rest. In your last year you have to write a paper with some field research on a topic that fits your track. Still not really like a science fair though.