Try playing with door sensors. They are simply two magnets that are open or close. The detection effect is very visual. The sensor opens or closes and you ge

Try playing with door sensors. They are simply two magnets that are open or close. The detection effect is very visual. The sensor opens or closes and you get a signal. Door sensors have come a long way and are wifi-enabled these days [1]. Link them to your phone (or iPad if doing a projection on TV). Tape the sensors to door, window, drawer, your jacket, etc. Open them and see the signal sent to your phone. [1] https://www.amazon.com/s?k=door+sensor+wifi https://www.amazon.com/s?k=door+sensor+wifi