Composing and Decomposing IS NOT adding and subtracting

I remember when the NEW TEKS first released, I was super confused about the composing and decomposing language. It sounded like "putting together" to me, so I naturally associated it with addition. And decomposing means to break apart numbers, so I naturally associated it with subtraction.

But after surveying many of the the state's supporting documents and reading one of my now favorite books, Teaching Student Centered Mathematics (by John Van deWalle) and Developing Number Concepts by Kathy Richardson; I began to get a deeper understanding of the concept of composing/decomposing.

"To conceptualize a number as being made up of two or more parts is the most important relationship that can be developed about numbers." (Van deWalle 2006, pg 26)

This was such a great quote that helped me make the connection that composing and decomposing is the conceptualized foundation that helps support students understanding for addition and subtraction.

So bottom line is composing and decomposing is NOT addition and subtract, but it lays the foundation for students being able to fluently add and subtract, mentally!




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