Science Olympiads are fun ways to learn about science. There are three major categories: Division A (elementary school: grades K-5), Division B (middle school: grades 6-8), and Division C (high school: grades 9-12). You choose a category and then participate in a competition in that area.
Here are a few videos about Science Olympiads.
Bridge Building Science Olympiad
Wheeled Vehicle Science Olympiad
Food Science Science Olympiad
Crime Buster / Forensics Science Olympiad