Building Powerful Numeracy: Subtraction

Are you students having a hard time with multiplication, division, or understanding complicated formulas? Chances are they need help thinking and reasoning about subtraction! Subtraction has huge impacts on students proficiency, understanding, and speed with so many higher math topics.

Subtraction can mean removal or difference – you can either remove a quantity from another or find the difference between the two quantities.  The traditional subtraction algorithm suggests removal, and thus many students think of subtraction only as removing.  Students can be stymied when a situation requires finding the difference, or when a formula can be better understood by thinking of the subtraction as finding a difference, such as in the slope formula. We all need to be fluent using both meanings of subtraction.

Some accessible, yet powerful, subtraction strategies use the difference meaning of subtraction. For example, you can think about 1,011 – 999 as removing 999 from 1,011.  Or you can also simply find the difference between 999 and 1,011. An open number line is a great way to show that relationship.

Photo Aug 11, 1 44 29 PM

But for a problem like 1002 – 7, you might just want to remove the 7 from 1,002.

Photo Aug 11, 1 54 04 PM

Each of these problems have many opportunities for error if students used the traditional subtraction algorithm, as it requires several regroupings.

Come to the Subtraction workshop to develop your own subtraction prowess and learn how to build it in your students too!

This workshop is appropriate for teachers  grades 2-12.

Click here to register for workshops.