Illuminations This site, from the National Council of Teachers of Mathematics (NCTM), features complete lesson plans, mobile games for students, interactive activities, and brain teasers.
Illustrative Math High-quality educational resources for teachers and students. Excellent math tasks, videos, lesson plans, and problem-based curriculum modules
Woot Math Woot Math offers adaptive practice for teaching rational numbers and related topics, such as fractions, decimals, and ratios.