GregTangMath.com: GregTangMath strives to provide unparalleled math lessons for students as well as professional development for in-service teachers. Games, puzzles, and other resources, like free downloads, worksheets/word problems, math centers. Grades: K–6
Desmos: An online graphing calculator that students can use for free. Includes a teacher-centric activity builder for creating digital math activities. Grades: 9–12
GeoGebra: Another graphing calculator for functions, geometry, algebra, calculus, statistics, and 3-D math. Includes practice sheets. Grades: 9–12
Numberock: Teachers know that one of the best ways to make sure learning sticks is through song. Numberock features ad-free music videos of songs about math topics, like fractions, money, and integers, produced by an Emmy Award–winning studio. Numberock also has anchor charts, worksheets, comics, games, and more. Grades: K–5; cost: Some videos are free; free trial
Coolmath Games: Yes, math games can be cool! Check out the hundreds of games on this site and on Coolmath4kids. Grades: K–12; cost: Free; $ ad-free version
Funbrain: Funbrain has been helping students learn key math concepts and develop crucial skills since 1997. Students can choose from a slew of games. The best part? It’s all free! Grades: PreK–8; cost: Free