People on HN are often interested in Math and in education. I'll mention the Journal of Inquiry-Based Learning in Mathematics http://www.jiblm.org/.
(Just from my personal experience: I teach the Intro to Proofs course in this way, and use a book on proofs that I wrote in this style http://joshua.smcvt.edu/proofs. It has a lot of advantages. One is that at the end of the semester everyone, even those on the lower half of the bell curve, is still highly involved and understanding everything that is happening. That's important to me; for instance some of the folks in the room will go on to be teachers, either in high school or in elementary school.)
(Just from my personal experience: I teach the Intro to Proofs course in this way, and use a book on proofs that I wrote in this style http://joshua.smcvt.edu/proofs. It has a lot of advantages. One is that at the end of the semester everyone, even those on the lower half of the bell curve, is still highly involved and understanding everything that is happening. That's important to me; for instance some of the folks in the room will go on to be teachers, either in high school or in elementary school.)