Math Pickle is a free site that offers dozens of fun and challenging math puzzles for students of all ages. The puzzles are designed to foster collaborative problem solving over the course of 45 to 60 minutes. Almost all of the puzzles are presented as a series of small, connected problems that students need to solve to complete the puzzle presented to them. The puzzles can be viewed as slides and or downloaded as PDFs.
Expii Solve is a series of seventy sets of word problems. Within each set there are five problems aligned to a theme. For example, the most recent problem is about cell phones and distance that radio waves can carry. The problems within each set on Expii Solve vary in difficulty so that you can pick the one(s) that best suit your students. Or you can let your students register on the site and self-select the problems that they want to tackle. In fact, that is how the site is intended to be used. Students can get instant feedback on their answers to the problems that they try to solve. Students who need a bit of help solving a problem can use the hints and tutorials linked at the bottom of each problem page.