Among the favorites:
Tenzi - Throw a set of dice (Tenzi is supposed to be with 10 dice, but we started with 5 and worked our way up.) Decide on which number you're going to "collect." Keep the dice showing that number and throw the rest of the dice again. Keep any of the number you are collecting, and then throw the dice again...until all your dice are gone. With older children this can be a speed game. This works on counting and number recognition for the smaller kids:
War - Remove non-numeric cards from the deck and deal the rest between 2 players. Players turn up their top card at the same time. Whoever has the higher number takes the trick. Keep playing until all the cards are gone. Then practice counting even higher by counting who has the most cards!:
Hide and Eek - This game works on the concepts of odd/even and higher/lower for numbers 1-100. There is also a little memory work involved for cards that do not remain face-up. And there is some strategy for where to move the mouse once you've rolled the dice and know whether you're trying to land next to numbers that are odd/even or higher/lower:
Scrambled States of America - This game works on letter recognition (example: find your states the begin with the letter "A") and syllables (example: find a state whose capital has 3 syllables) along with state recognition by shape and location. Fun and quick enough for the big kids to enjoy with the little kids. Bigger kids will catch on to state capitals and nicknames, but this game is not so rigorous that I would include it in the learning games for middle schoolers:
