Sometime before I was eight years old (this becomes important later), my mom taught me about negative numbers. This excited my curiosity, and I remember walking into my mom's bathroom as she was getting ready to shower to ask her what happened when you divided a positive number by a negative number. So yes, my mom is a saint (she answered my question, and got in the shower).

Later, in third grade, a substitute teacher was ridiculing the work of a student who'd had the temerity to subtract a larger number from a smaller number. Everyone knew that was impossible. Full of indignation as only an eight-year-old Galileo can be, I stood up (I don't know why I couldn't have just raised my hand like a normal person) and protested that it was entirely possible. For my trouble I shared in the ridicule, and later got a talking-to about "teaching things when people are ready for them."

It might look like it, but I'm not leading up to a critique of the elementary school system. My point is different entirely: math can be fun. Maybe not all at once and with Consequences If Not Correctly Learned, and maybe "fun" in the way programming is fun (i.e. still hard), but it's still fun.

You've got a long while before your kids have that drummed out of them. Use it. My mom was a Dance-turned-English major, but she still answered my absurd questions in absurd circumstances. I wish everyone could have my parents.