I've posted many pictures of Brooke & Courtney playing 'scientist'. They love to experiment with various substances to see what they can do.
This morning we made Gak. Gak is a silly putty-type substance that can be made with the right combination of Borax, Elmer's Glue and water. For effect you add food coloring.
The result is a great deal of fun. From there they go to an old standby--vinegar and baking soda. Courtney especially loves doing this to watch the resulting eruption.
Kids love to learn. It's as natural as eating. But when I was in grade school, science was reading a chapter from a book, answering questions, reading more, answering more questions, etc.
Today grade-school science is often hands-on experimentation. That's the way it should be.