Speaking of crypto treasure-hunts and math circles…I just found these educational materials from the NSA. There are dozens of lesson plans for topics ranging from probability to geometry. They’re very complete, including clear instructions for the teacher (or parent, or math circle leader for that matter), and nice activities to print out for the students.
Wonderful math educational materials
May 31, 2009
Between this, Wolfram’s recent re-dedication to K-12 education, and KenKen, this has been a fruitful month for me in the math education quest.
More broadly, I’ve found the matheducation reddit page to be a very useful place to discover stuff like this.