Signed Numbers: Colored Counters in a “Sea of Zeros”
November 10th, 2011
The “colored counter” method is an old tried-and-true method for teaching the concept of adding signed numbers. However, to show subtraction with the colored counter method has always seemed painful to me … that is, until I altered the method slightly.
Now all problems are demonstrated within a “Sea of Zeros” and when you need to take away counters, you can simply borrow from the infinite sea. Voila! Here’s a short video to demonstrate addition and subtraction of integers using the “Sea of Zeros” method. You can print some Colored Counter Paper here.
Video: Colored Counters in a Sea of Zeros
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Great demo! It would have been nice to see one more problem like -2-(-4)=2 to show that the process also results in a positive answer.
I really like this method. Do you know if there are any online games that use it? I usually just use the number line method, but subtracting a negative number really gives my students trouble. Somehow their intuition is wrong, and they have trouble believing me when I insist that 6 – (-4) = 10, for example. Maybe if they played with counters for a while, that wrong intuition would fade a bit.