Basic subtraction games can help your child develop familiarity with simple subtraction problems. Many different online games focus on basic subtraction, such as “Subtraction Machine” (see Resources). These games present your child with a simple subtraction problem and then ask him to provide the answer. Most games in this style have a difficulty level, which can be gradually increased as your child becomes more confident in his subtraction. Alternatively, you can set your child subtraction questions in person. Present him with 10 pennies and ask how many he would have left if you took away six, for example. Demonstrate with the pennies to help him understand the basics.
Some games focus specifically on the process of subtracting 10 from any given number. One example of an online game like this is “10 Less Shootout” (see Resources). These games generally present your child with a number and several options for an answer. Your child has to choose the correct answer from the available options by finding the number that is exactly 10 less than the original number. This basic formula can be applied to a variety of situations to make online games. “10 Less Shootout” focuses on a soccer penalty shootout, and the player scores a goal by selecting the correct answer. Alternatively, for a hands-on activity, group 40 matchsticks into bundles of ten, and then leave a few more in another pile (less than 10). Ask your child to subtract 10 from the total number of matchsticks. Help him by reminding him that all he has to do is take away one bundle to get the answer, the smaller group doesn't change.
When your child is confident with basic subtraction, speed related games can be a valuable way of increasing his fluency. Games related to speed present your child with different sums which must be answered as quickly as possible. Set your child around 100 questions and challenge him to answer as many as possible in two minutes. Use a stopwatch or a timer to time his progress. Make the first set of subtractions relatively easy (using numbers less than 20), and then write him a group of more difficult ones. Tell him each time thirty seconds is up, and then count down the last 10 seconds to make it more exciting.
Advanced subtraction games use harder problems to really push your child’s abilities. One example of an online advanced subtraction game is “Subtracting to Win a Million” (see Resources). More complex questions are included on games like this, so only children confident in their abilities should attempt them. Without using the Internet, you could create a neat activity by getting your child to set up a store and price his items. Get him to use unusual prices such as $4.74, not rounded up to tens. Pretend to be a customer buying an item with a five, 10 or 20 dollar bill and ask him to work out the change you need. Three digit numbers or even larger ones can be included on games like this, and you can give hints to help your child along if he gets stuck.