Summer School - Math

Counting

Towers Up -counting with blocks
Gumball Counting - Play dough, do I need to say more?
Number Bowling
Dump Truck Counting 

Number Recognition 

could also be used for math facts - instead of just asking for the number ask a problem with that number as an answer

Flyswatter Math Game
Water Balloon Target Practice 
Coloring Race
Egg Carton Number Toss
Math Tunnel Game

Addition/Subtraction

Maths Chasey  - be the last one standing
Eleven - adding and subtracting with playing cards
Tens Go Fish - card game similar to go fish
Snap plus one - a card game
Fun Subtraction Game - a card game

Multiplication/Division

Jumping to 100 - skip counting with pillows (could be easily modified into an outdoor game)

Fractions/Decimals/Percents

Fraction Bingo
Fractionopoly - life sized board game