The other day, DS8 asked me if I could explain pi to him. He thought he was being tricky, and said it would take forever to explain because pi never ended. I told him I could explain it in a single sentence. (pi = the ratio of the diameter of a circle to its circumference.)

While I was explaining, DS6 insisted I explain to him, too, and was far more excited to discuss it than DS8. DS6 then got a bunch of different things for us to measure (e.g., cake pan, plates) and test whether we could ALWAYS determine what the circumference would be from the diameter. It was amazing to see him be able to do the multiplication, and understand the concept.