Here are resources that are great to help your child improve their mathematics skills!
http://www.coolmath-games.com/ A site of mathematics games to improve skills.
http://www.mathplayground.com/games.html More math games.
http://mathforum.org/ The Math Forum is place to ask math questions, to get extra help with math or to investigate a math topic.
http://www.aaamath.com/ AAA math provides tutoring and lessons in math topics for free!
http://www.figurethis.org/index.html A site with fun activities to involve the whole family in math
http://www.funbrain.com/numbers.html Fun math games for kids.