Our four year old has just become super-interested in numbers. All of a sudden they want to do lots of counting together, and are asking questions like: "why does 12 have a one and a 2?"<p>I told them about prime numbers earlier this week, and now I'm fielding questions about prime numbers that have pretty much exhausted my knowledge.<p>For obvious reasons, I'd love to encourage this interest in numbers, if it stays fun. I could really use some pointers to activities, books, etc about counting and math -- ideally, targeted for preschool age -- but stuff for later would be great, too!