Here are some good resources for math practice. If a link does not work, highlight the whole link, right click on it, and click "open link in new tab".
http://www.kidsmathgamesonline.com/
http://www.sheppardsoftware.com/math.htm
http://www.topmarks.co.uk/maths-games/hit-the-button
http://mrnussbaum.com/math-for-kids/
Pearson Math Games Grades 1-6:
https://media.pk12ls.com/curriculum/math/gamecenter/en_US/enV2-grade-1.html
https://media.pk12ls.com/curriculum/math/gamecenter/en_US/enV2-grade-2.html
https://media.pk12ls.com/curriculum/math/gamecenter/en_US/enV2-grade-3.html
https://media.pk12ls.com/curriculum/math/gamecenter/en_US/enV2-grade-4.html
https://media.pk12ls.com/curriculum/math/gamecenter/en_US/enV2-grade-5.html
https://media.pearsoncmg.com/curriculum/math/gamecenter/en_US/enV2-grade-6.html
Math is Fun: This is a great website with lessons multiple topics; you can also search for a topic. There are games and puzzles for practicing skills as well.
https://www.mathsisfun.com/index.htm
Arcademics: This is a fun site with lots of different skill builder games at multiple grade levels.
Multiplication.com: Another site with fun games for practicing facts.
http://www.multiplication.com/games/all-games
Math Playground: Lots of fun online math games.
http://www.mathplayground.com/
Math-Play.com: This website organizes games by grade level and topic.
Equivalent Fractions Practice:
http://www.sheppardsoftware.com/mathgames/fractions/memory_equivalent1.htm
Convert fractions, decimals and percents:
http://www.sheppardsoftware.com/mathgames/fractions/FractionsToDecimals.htm
http://www.visnos.com/demos/percentage-fraction-decimals-grid
Practice identifying algebraic expressions:
http://www.math-play.com/Algebraic-Expressions-Millionaire/algebraic-expressions-game.html
Practice solving one step equations:
http://www.math-play.com/soccer-math-one-step-equations-game/one-step-equations-game.html
Games to play to practice coordinate graphing (ordered pairs):
http://interactivesites.weebly.com/coordinates.html
Telling Time:
http://classroom.jc-schools.net/basic/math-time.html