National Council for Teachers of Mathematics provides free activities resources on their site that can be sorted by grade level from elementary through HS
Comprehensive collection of math vocabulary resources includes CCSS aligned math vocabulary word lists (left side). Don't miss the great activities and websites to build vocabulary skills (right side)
DigitWhiz is an online math program that guides kids ages 8+ to master key foundational skills in five areas: Multiplication, Division, Integer Operations, Like Terms and Solving Equations. DigitWhiz evaluates, prescribes games/activities and guides kids to mastery in a fun and effective way. Kids earn points along the way redeemable at the Digi prize store for virtual rewards. Also, kids earn awards and downloadable certificates for mastery achievements.