Children learn science best and understand scientific ideas better if they are able to investigate and experiment. This is especially true for younger children. 

Hands-on science can also help children think critically and gain confidence in their own ability to solve problems. Some science teachers have explained it this way: 

What engages very young children? Things they can see, touch, manipulate, modify; situations that allow them to figure out what happens--in short, events and puzzles that they can investigate, which is the very stuff of science.