Subtraction Games that teach the strategy of:
Subtracting the same two numbers always makes 0
Over time we have learned to call this strategy "Subtracting Twins" because it gets very confusing when referring to strategies in this category. For example, Subtracting Doubles can refer to problems like this: 16 - 8 = 8; 6 -3 = 3; 4 - 2 = 2. Adding Doubles refers to problems like: 10 + 10= 20; 4 + 4= 8; 6 + 6= 12. Instead, subtracting twins creates a visual image for kids of subtracting 2 of the same numbers.
I always act really silly with this one. I say: I have 8 cookies and I ate 8 how many do I have? I have 6 eggs and I slurped down all 6, how many do I have? Most kids get this concept in seconds.
Undertanding this simple strategy will pay off down the road when your child is learning about positive and negative numbers.
Using a numberline is a visual way to explain this strategy to your child. Keep a numberline handy while your playing the games and/or doing homework!
1. Not your ordinary Flashcards: When you are doing flash cards with your child, silently hold each flashcard in front of your child- tell him/her not to say the answer to the flashcard. When they see a "Twin" fact have them shout "TWIN" and put that card in a seperate pile.
2. Sidewalk Subtraction: Have your child draw twenty boxes or x's on the driveway with sidewalk chalk. Now have them skip, jump, run, hop on one foot, etc. to a certain number, then subtract that same number ( of course they will always end up where they started). For example, you might say 18....now take away 18. After a few turns most kids just stay in one place with a giant grin!
3. Here is cool chant that you might add to one of the above games:
Numbers the same?
Zero's the game.
I was surprised that I had to explain this idea to my daughter. Telling her that subtracting twins always makes 0, helped.