FreeRice.com: Academic practice with a purpose

Earn actual grains of rice to feed the hungry while you practice basic math and other subjects!
http://www.freerice.com/

Math Games I Have Known

Recommended math games for 5th hour!

Ordering numbers
Number Balls (click on the rotating balls starting with the lowest value first, includes negative numbers)
http://www.coolmath-games.com/0-numberballs/index.html

Basic Addition and Subtraction

Feed Fribbit Addition
http://www.coolmath-games.com/0-feed-fribbit-addition/index.html

Math Lines Addition (Zuma-style game)
http://www.coolmath-games.com/0-math-lines/index.html

Math Picture Puzzle (choose the right sum to reveal each part of the picture)
http://www.thekidzpage.com/learninggames/math_picture_puzzles/addition-to16-halloweencat.html

Feed Fribbit Subtraction
http://www.coolmath-games.com/0-feed-fribbit-subtraction/index.html

Subtraction Blast (shoot numbers to subtract them from targets--fast and furious!)
http://www.coolmath-games.com/0-subtraction-blast/index.html

Memory Games

Concentration (slow-pace, big graphics for easy recognition)
http://www.coolmath-games.com/concentration/index.html

Pattern Memory
http://www.coolmath-games.com/0-patternmemory/index.html

Fractions
Fractone (add fractions that total 1)
http://www.coolmath-games.com/0-fractone/index.html

Fraction Splat!
http://www.coolmath-games.com/0-fraction-splat/index.html


Harder Stuff

Mathlines X Factor (choose combinations that multiply to 12 and higher)
http://www.coolmath-games.com/0-math-lines-xfactor/index.html

Math Man (like PacMan, but you can only eat the ghosts with the right answer, requires understanding of Order of Operations)
http://www.coolmath-games.com/0-math-man/index.html