Mathematical games interesting to both you and a five-year-old child
I've been writing little one-page javascript pages to introduce my four- and six-year-old to various mathematical concepts like cardinality, place-value, sets, factors, equivalency, etc, etc:http://ideonexus.github.io/Explorable-Explanations/The boys love some of them (others not-so-much). Based on this article, I'm getting lots of ideas for new ones to code. Most of the code is original, but I try to be careful to give credit to anyone whose code or ideas I build upon.