If you have a budget you can go for robotics. I'd recommend getting a Lego Mindstorms kit, they usually come with ideas for builds (both hardware and software).

If you have a budget you can go for robotics. I'd recommend getting a Lego Mindstorms kit, they usually come with ideas for builds (both hardware and software). When I was presenting this to 10 year olds couple of years back they loved it! With mindstorms you can make it very interactive, you could easily do a show and tell of programming it with block diagrams. You will most likely have a lot of fun yourself!