There’s a limited number of things you can do while waiting for a kid to finish eating lunch. I try to avoid doing phone or computer stuff because screens have this intense hold on kids. The guy, for example, is captivated by the Ubuntu lock screen and could easily spend half an hour typing into the password field and clicking on stuff with the mouse. (I should test whether this brain-lock also happens with e-ink displays.)
So, yesterday, I tried drawing out a paper pattern for a 3D mountain. Mostly, I drew triangles. It’s a nice intersection of something that’s interesting for all of us.
It more or less worked out. It just didn’t occur to me that you need more triangles at lower layers of the mountain.