Math
K-12
A site filled with online math games for all kinds of basic math skills such as estimation, place value, and the four operations.
Math Games at Sheppard Software
A bunch of different games to practice addition, subtraction, multiplication, division, place value, coins, fractions, mixed operations, and telling time.
5-8 Years Old
Find games for addition, subtraction, time, shape and measures, more/less, odd/even, doubles, place value, and more.
K-3
A collection of online math activities, including number patterns, bingo, ordering, secret numbers, clock, simple quizzes, and more.
K-2
15 games designed to help children understand basic number concepts (kindergarten level). You can also download the games to play on your PC/Mac.
1st-6th
A large collection of interactive word problems, math games and puzzles for elementary school students.
Lots of interesting games, mostly for middle school, from Freudenthal Institute for Science and Mathematics Education.