Couch an addition lesson in terms of a "think fast" timed game of skill. Give your child a grocery receipt with the total whited out and give him 30 seconds to add it up in his head. Or, if he's learning fractions at school, use a recipe to demonstrate how fractions may be used in real life, and ask him to add fractions to figure how to alter a recipe to serve more people. Make sure he has some skin in the game: make the reward for success a trip to the drive-thru or a movie ticket.
Instead of giving your child dry subtraction lessons, play an online game with her that requires her to keep track of resources, such as a town-building game that requires players to use lumber, stone and metal. Games that require players to keep track of resources, as they are used, encourage subtraction skills. Questions to ask might include: "Do you have enough wood to build that farm?" or "Will you have enough stone afterwards to build a second farm?" Alternatively, encourage your child to associate subtraction with real life money skills by giving her five dollars. Tell her, "You can buy anything you want with this, but I want exactly $1.25 in change."
Some kids love repetitive songs; the memorization required for call-and-response is a fun challenge. Download multiplication songs from online websites that offer call-and-response in waltzes, marches, cha-cha and even rap styles. Alternatively, play the more old-fashioned, but effective, multiplication flash card games that your own parents used with you. Ask: "What's 5 times 5?" and use the flash card only to show the correct answer. Be sure to reward success with some kind of prize or privilege, to teach your kids that math skills can pay off.
Introduce your child to online game sites that prompt with division problems. These games can take the form of baseball, arcade games, adventure quests or trivia. Typically, the child can't advance to the next level until he provides the right answer. These games keep track of your child's answers, automatically tell him if they're wrong or right and display the correct answer if he answers correctly.