If you are a teacher fortunate enough to have classes in rooms with a computer/video system, or if you want your kids to play educational English computer games at home, then check out the games on these websites:
http://www.manythings.org/vocabulary/
http://eslgamesworld.com/members/games/grammar/index.html
You'll have to search the sites for the appropriate level games. Some of them are great, some not-so-great.