I stumbled across this free math course from Annenberg Media for high school teachers and adult learners, and I fell in love. It looks incredibly interesting to me, so I thought I'd share.

I plan to use it myself this summer to learn more about the history of math and how to think math instead of "plugging and chugging," and then hopefully next year I can teach DS6 from what I've learned.

http://www.learner.org/channel/courses/mathilluminated/about/
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Kriston