SAGE is a free, open-source computer algebra system. [more inside]
posted by kaibutsu on Oct 30, 2009 - 37 comments

MathTV is a real problem solver for many. It is also found on YouTube, and is free. Here is some background.
posted by Brian B. on Mar 21, 2009 - 8 comments

EducationFilter: California becomes the first state to mandate all 8th graders take Algebra; in part because U.S. students constantly trail their peers from other nations in mathematics. At least one person thinks it's a bad idea ("If only 25 percent of this nation ever earns a college degree, why insist that all children take algebra in eighth grade?"). Here's the algebra curriculum 8th graders will have to learn. [more inside]
posted by jabberjaw on Jul 10, 2008 - 124 comments

Interactive mathematics miscellany and puzzles, including 75 proofs of the Pythagorean Theorem, an interactive column using Java applets, and eye-opening demonstrations. (Actually, much more.)
posted by parudox on Dec 1, 2007 - 11 comments

The Klein Four is a group of math students at the Northwestern University who delight in bringing you various lovely, well-sung A Capella songs infused with their very own and very nerdy flavour. They're not the newest of the web, having released their first CD in 2005, but witty lyrics and five-part harmonizing are definitely worth checking out. I did do a search for this and didn't find anything. Please don't kill me.
posted by Phire on May 23, 2007 - 14 comments

The Value of Algebra: "Gabriela, sooner or later someone's going to tell you that algebra teaches reasoning. This is a lie propagated by, among others, algebra teachers."
posted by daksya on Feb 16, 2006 - 190 comments