Wednesday, January 25, 2017

Decomposing with Addition Notations

With so many ways now to add, I find it nice to have a consolidated page for some of the methods being used. I have my favorites which I tend to focus on, but let's jump in from the beginning. Well, from the beginning of addition in my third grade class that is.

While students come to my class with different methods to add already, we start playing with number lines. Number lines are versatile and easy to adjust to a student's level. Building to friendly numbers is key at first until students are able to comfortably add combinations of tens across the hundred line. Switching addends to start is a great way to get students thinking of how to solve a problem and reinforce the commutative property. It could be a lot easier to start from the second addend.

From number lines, we head on to arrow language. I love arrow language! Number lines are great, but can take up so much space. Once students understand the distance with addition on number line jumps, using arrows to represent partial sums is a much more concise notation.

Check out arrow language worksheets here.

Decomposing is so useful in math! Here are a few notations for solving addition with decomposing. You'll notice arrow language is one of the notations as well. After trying out different notations in class, students are free to choose the notation that fits them best for solving addition. We do work towards more efficient uses of the notations though, so students will not get stuck with a long, cumbersome notation.

For a free video explaining these notations, check out Decomposing: Addition Notations. It also comes with the files for the examples talked about in this post.) The video also compares these notations to the traditional algorithm.

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