I taught middle school math and the concept of simplifying algebraic expressions seemed to be a hurdle my students just couldn't master. They seemed to think that x's could be added to x^2's or y's could be added to x's. They even added x's to numbers! What is a teacher to do? A fellow teacher gave me the initial idea for this easy way to help students to correctly combine like terms when they are learning how to simplify algebraic expressions. I'm not sure if she came up with it on her own or got it from somewhere else. Anyhow, I've expanded upon the idea and thought it was worth sharing.
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