Arcademics: Practice basic skills by playing games:
http://www.arcademics.com/games/grand-prix/grand-prix.html
Froot Shoot game (GCF)
http://www.sheppardsoftware.com/mathgames/fractions/GreatestCommonFactor.htm
Multiply Fractions Millionaire
http://www.oncoursesystems.com/school/menu/24524
Fraction Model
http://illuminations.nctm.org/Activity.aspx?id=3519
http://www.arcademics.com/games/grand-prix/grand-prix.html
Froot Shoot game (GCF)
http://www.sheppardsoftware.com/mathgames/fractions/GreatestCommonFactor.htm
Multiply Fractions Millionaire
http://www.oncoursesystems.com/school/menu/24524
Fraction Model
http://illuminations.nctm.org/Activity.aspx?id=3519