How to explain to a child that he must keep a certain distance from  people around him?
With the mechanical telephone!

Do you remember it?
Two glasses / jars a wire that connects them and if the wire is tight, the voice comes loud and clear.
So if you want to keep in touch with those you love and continue playing the wire must be tight and it takes at least a meter otherwise you don't hear anything and you can't chat with anyone!

In the Distanze series the photos that explain how the game works Distances/Distanze done!