Last year when I spoke at my daughter's school, I used a javascript version of rock, paper, scissors to get the kids involved in discussing programming. This year, I really wanted to give them something a bit more physically interactive, so I decided to do something with some Arduino Uno boards. Initially, I wanted to play a game via radio, but I don't have the materials I would need to do that. What I do have are push buttons and LEDs. Again, I'm using random numbers. I also wanted to show them some sensor reading stuff. The code is posted here.
Rock, Paper, Scissors: 2017
Distance Sensors: 2017