This is a quick writeup of a lesson on how GPS (or in general, satellite based navigation) works. I’d like to thank Jasper Vos and Michel Dingen of OBS De Notenkraker for the opportunity & the very useful feedback on the lessons!
Context

10-11 year old children mostly have phones here, and almost all of them turn out to have location sharing turned on with their parents. They also use their phones while on holiday to figure out where they are.

A smattering of kids here knew that phones use satellites for precise positioning, and one or two even know about GPS. So that is good!

It also turns out there is healthy interest in discovering how it actually works.