I’ve found it a bit difficult to explain the concept of evolution to a child below the age of 10. You run into a problem defining all those “things” involved – like DNA and reproduction and population and deep time. Those are tough for kids to grasp (especially “populations”, I’ve noticed). Check out this video with adorable graphics and rather easy to understand explanations.
It still contains some big words but try it out on your kids and see how they respond to it. I’m going to try an experiment myself.
The video is from the site Stated Clearly which includes other videos like it on related topics. Check it out.