On coins and buttons: Perhaps the children are intuitively comparing the areas of the convex hulls, a thing humans are good at, is an interesting mathematical p

On coins and buttons: Perhaps the children are intuitively comparing the areas of the convex hulls, a thing humans are good at, is an interesting mathematical problem, and could be the basis of interesting alternative mathematics. You could have a whole set of sessions with children exploring different arrangements of coins and noting that no matter how many you add within the hull, you don't get any 'more coin' (altering the plurality may help adults understand this problem.) If you have some button[s] and much more coin[s], can you add just one coin so that you have more coin than button? How far away do you need to add it?