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Open Number Lines

One day a colleague sent me some links to open number line resources. An open number line is number line with no numbers or tick marks. At first glance, the open number line was being used to solve simple addition problems with jumps to the right on the number line, or simple subtraction problems with jumps to the left. Students first needed to decompose the numbers being added or subtracted. For example, to add the number 37, one might jump 30 to the right, then 7 to the right. To subtract the number 21, one might jump 10 to the left, another 10 to the left, then 1 to the left.
After researching this topic further, I discovered that open number lines allow students to use many different mental math strategies to solve the *same problem*. Students could jump to the left, right, or in both directions to solve a simple addition problem. (The same was true for subtraction.) Thus, each student could solve the same problem in different ways. For example, a student could jump 40 to the right, then 3 to the left in order to add the number 37.

I am now smitten by open number lines! This open-ended model is a ground-breaking way to approach addition and subtraction for students of all abilities and students with special needs! It also makes use of place value skills. There is no longer only one way to add and one way to subtract. Open number lines provide unlimited opportunities for learning!

The use of open number lines facilitates number sense development and fluency in computational skills. Students learn to think flexibly about numbers and the strategies they use to solve problems. I hope to design an interactive open number line game in the near future.