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 Using Up/Down Over 10

Students would benefit from using 10 frames to support the development of this strategy. Students need to be able to decompose the number 10 in a variety of ways in order to access this strategy. 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.  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:

In Sherry Parrish’s book,”Number Talks”, refer to the sections on Making Ten and Adding Up.

Additionally, to help get students up over 10, students need to be able to:

• have automaticity with pairs that make 10

• be able to flexibly decompose numbers into 2 parts

• have 10 + n patterns