Computer games are a potential exception, say researchers involved in a math equity project supported by the National Science Foundation. Includes a poker game where students can experiment with what they've learned. This is a separate area and requires a free password to enter. A math professor offers Middle-L listserv members a simple lesson that allows students to explore the meaning of Pi. The site was commercial but all materials are now available at no charge.
Students learn some practical geometry and a little algebra too.
A fun project from Swathmore College, with student hints, teacher help, monthly projects, and awards. Several hundred students participate each week. Great lesson idea richly described. Nicely done by media specialist. The CPM mathematics program combines traditional mathematics education with a more contemporary focus on complex problem-solving.