Math Strategy: Using Up/Down Over 10

What is the Math Strategy: Up/Down Over 10?

Math Strategy: Up/Down Over 10
Math Strand: Number Sense and Numeration



On Lawson’s Continua:
Up/Down Over 10 can be found in the Addition and Subtraction Continuum.




Overview:
Once students have an anchor of 10 students can be encouraged to use the strategy of Up/Down Over 10. This strategy is also known elsewhere as decomposing to make ten. This strategy allows students to be flexible and quickly complete adding and subtracting situations.

When adding, students take one addend and leave it whole. Then, they take the other addend and decompose it to make 10. The remaining amount is added to the ten that was made.
When subtracting, students decompose the subtrahend to subtract an amount that leaves 10 remaining. Then the students would subtract the remaining amount to find the difference.





Supporting Students to Use Up/Down Over 10:
Students would benefit from using 10 frames to support the development of this strategy. By using the ten frames to join two amounts, while connecting the numerical version of the adding (or subtracting), students will be able to gain a stronger grasp of this strategy. See the example below for 16 + 8:

Examples of Up/Down Over 10 from Lawson's What to Look For, pg 16:




Once students are confidently using this strategy, encourage them to use the strategy with larger numbers. For example, students could add 350 to 90 by taking 50 from the 90 to join it to 50 from the first addend. This would create 100. Once the 100 is joined with the 300 to make 400 the remaining 40 from the second addend can be joined.

Where to next:
Consider using activities that promote the development of the anchor of ten strategy so they are able to access the Up/Down Over 10 strategy. Some suggestions can be found in the text, “What to Look For” by Alex Lawson, on page169, 170, & 200. Once students have the anchor of ten, support them to see the numbers that live inside a number that can be used to get to ten. In Lawson’s text, there is a mini lesson that supports the development of this strategy. To support Down Over 10, go to page 201 of Lawson’s text. In Sherry Parrish’s book, Number Talks, refer to the sections on Making Ten and Adding Up.

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