http://softschools.com/math/games/algebra_practice.jsp
http://math-play.com/6th-grade-math-games.html
http://www.toonuniversity.com/free/math-games-4th-6th_a.asp
http://www.dr-mikes-math-games-for-kids.com/sixth-grade-math-games.html
http://www.internet4classrooms.com/skills_6th_original.htm
http://illuminations.nctm.org/Activities.aspx?grade=3
http://shodor.org/interactivate/activities/
http://www.softschools.com/quizzes/math/
http://www.softschools.com/grades/6th_and_7th.jsp
http://www.ixl.com/math/grade-6
http://www.ixl.com/math/grade-7
http://www.ixl.com/math/grade-8
http://www.aimsedu.org/Activities/upper.html