Please note that I'm not pushing anything re AP computer science. I'm simply prototyping how to teach a regular, garden variety mathematics curriculum with some computer language as part of the mix. This is the next step after the current "graphing calculator" craze is over. Of course, *I* know and understand what you're doing. The problem is that others won't. We wrote a proposal to NSF in 1996 to re-do the mathematics curriculum with Scheme. We also threw in physical sciences and the dismal science. As soon as you mention "computer" you're no longer considered a "math" person. They need to bring in a "computer specialists" even if they agree that what you do looks like math. Of course, the CS person won't have a clue about this funny stuff you're doing. But then again, this fraction stuff looks like exact real arithmetic and, oh yes, btw, that was done in the AP CS case study from 1994.7 to 2000.5, so you're behind. See how it works? Been there. Done that. Next? -- Matthias