I tried a new activity this summer. I was worried the shape toys would feel too “baby” — but combined with “build every Johnson Solid We can” (which is hard) it was just about right.

With older kids I’d withhold the images and just tell them how many of each kind of face.

I don’t have a good elementary explanation for why it’s sometimes possible to build an “invalid” solid— would love any suggestions on that. #mathematics #math