Here is a list of people who blog about mathematics from David Wees (as a Google Reader bundle), or mathematics education. It is incomplete... but will get updated periodically.
"MathleteBlogs.com is a resource for mathematics teachers to connect their math students with peers from around the globe to enhance their mathematical learning experience from K-12."
"The famous Swiss psychologist Jean Piaget stated: "to understand is to invent", highlighting the active nature of the learner. The above discussion provides an outline of the theoretical foundation on which Inquiry-Based Learning rests. Furthermore, it provides a summary of the mounting evidence that students who are given the opportunity to learn mathematics through inquiry develop better strategic competence and deeper conceptual understanding of mathematics. "
"the more I questioned the wisdom of this rigid requirement. And eventually my message for students changed from you must show your work to you may show your work. Here's why." The goal of showing work is to understand thinking ... requiring showing work may hinder mathematical thinking by emphasizing computation.
Videos produced by MIT faculty for math/science concepts that have applications or demonstrations that usually attach to the world around us and higher mathematical thinking