Using Chip Models for Adding/Subtracting Integers
My district has adopted a new curriculum, Connected Mathematics 3 (CM3). Right now we are working on Integers and CM3 has students use a chip model to introduce adding and subtracting integers. I LOVE this type of model for adding. I've used it for years (and even developed my own game called " Close to Zero "). For subtracting, I'm torn. It is not the way my mind thinks about integers. But in an effort to avoid putting my preferences on my students, I wanted to make an effort to teach it this way in case it helps some of my students "see" what is going on with subtracting. It works like this: Pink = Negative and Blue = Positive If I have a problem such as -4 - 3… Start with 4 pink chips to represent -4: We want to subtract positive 3. There are not 3 blue chips available… so add 3 zeros (a pair of a positive and negative). We can do this because adding zeros does not change the value. Now, go ahead and subtract 3. You are