Just recently, I found out that he's written in much more depth, and has lots of intriguing essays gathered together here. My favorite essay so far includes thoughts on how to talk with your child's math teacher about math:
These are some of the questions I would ask [the teacher]. Is she interested in mathematics? Does she know the subject well? Does she believe the mind is a pot to be filled or a fire to be ignited? Does she like to solve problems? What kind of problems? Does she encourage the students to show perseverance when the riding gets rough, tolerance towards opinions held by others and pride in work well done? Does she teach the students general problem solving skills? Does she teach them guessing, pattern spotting and the difference between a guess and a proof? Why does she like to be around children? Why does she like to teach mathematics?
A few of Jan's puzzles will be featured in my soon-to-be-published book, Playing With Math: Stories From Math Circles, Homeschoolers, and the Internet.