Let's build on my previous Instructable, and assume that you have a SWIM (Sequential Wave Imprinting Machine). I gave my 9-year old daughter a SWIM and she was able to use it to visualize radio waves from a microwave motion sensing burglar alarm.
We're surrounded by surveillance cameras and computer vision cameras watching us, e.g. Internet of Things (IoT), yet we ordinarily never get to see how these things see us. With SWIM you can make visible the otherwise invisible "rays" of sight as if emanating from these smart "things" that surround us.
The system we use for teaching these principles is the SWIM that was outlined in a previous Instructable.