With as much time as kids spend in front of the computer have them play fun learning games or take advantage of some of these great learning tools over the summer: 
 
RESOURCE SITES FOR PARENTS AND STUDENTS 
 
FunBrain: http://www.funbrain.com 
 
Scholastic Kids: http://www.scholastic.com/kids 
 
Homework Spot: http://www.homeworkspot.com 
 
PBS Kids: http://pbskids.org/games 
 
Game Goo, Learning that Sticks: http://www.earobics.com/gamegoo/config.html 
 
Aplusmath.com!: http://www.aplusmath.com 
 
S.O.S. Mathematics: http://www.sosmath.com 
 
Math.com: http://www.math.com/students/practice.html 
 
University of Cambridge: http://nrich.maths.org/public