In my explorations of math education this fall, I have been encountering a wide range of resources for math teachers. Many list such a wide range of problems, resources, and tools that even a good search strategy is not helpful in finding the items that are unique to the site. Open Middle is a site that has a relatively small, but very useful collection of problems for math instructors. Many of the problems are puzzles with hints and a solution provided.
I am a fan of using math to solve real-world problems, and I find those connections are essential for many math students. The problems and puzzles on this site tend to be more “abstract” and little is given to put the problems in any real context. Still, they are a welcome addition to the classrooms in which I work.