Educational Games

Sudoku is an educational game. It makes your brain work hard. Not all people like Sudoku but if you want a challenge you should try it. http://www.sudoku.com/

http://www.arcademicskillbuilders.com/games/grand_prix/grand_prix.html
This is a racing game but you need to do math. You don't control the car you just control the speed. You answer simple addition problems.