The Open Number Line

Changing the way we subtract...

At the beginning of third grade the third grade team of teachers drill addition and subtraction strategies. We believe that it is best for the students to have a variety of strategies available to them when solving an addition or subtraction problem. I like to have my students visualize these numerous strategies as a suitcase that that have by them at all times - then they can pull out the appropriate strategy whenever needed.

One of the strategies we teach for subtraction is the open number line. (You can also teach it for addition, but I try not to teach this strategy for both at the same time as it causes confusion with the students) The students really enjoy this strategy because it is fun and easy. As a teacher, I really like the open number line because it fundamentally teaches what subtraction is.

Soon I will have some pictures of how to use the open number line to solve an addition problem, along with some student work.