This is a fantastic engineering challenge - use Legos to build a track for hexbugs! There is a video in the post that shows how it works. My son is now working to figure out how to get his hexbug to go up a Lego ramp - hasn't perfected it yet, but it's a great project.
STEM for Kids: 10 Awesome Homemade Marble Runs- Make marble tracks and marble mazes using Lego bricks, pool noodles, cardboard tubes, and more in this fun collection of science activities for children. (Great boredom busters)