Addition and Subtraction Facts to 18

Strand: Number
Outcome: 10

Step 5: Follow-up on Assessment

Guiding Questions

What conclusions can be made from assessment information?
How effective have instructional approaches been?
What are the next steps in instruction?

A. Addressing Gaps in Learning

If students are having difficulty in solving the basic facts using strategies, check for the following:

Do students know their addition facts using strategies? If not, go back to teaching strategies for addition before continuing any work on subtraction.
If students need addition work, can they solve for the facts with manipulatives? For example, can they show making tens if they have a ten frame? Start with small numbers for the addends. Make sure each doubles-related strategy is in place. Are students reverting to counting on for most facts? Have the students practise with flash cards that cue them to think of the strategy and how to use it. Play more games that reinforce the strategy. Be sure that students have mastery of the combinations for ten before revisiting the making tens strategies. Also, check how students visualize the teen numbers. For example, ask how they see a number like 16. Do they report visualizing 10 and 6 more or do they report 1 and 6? If the latter is the case, they need to work on place value before moving forward.
If students have addition strategies but are struggling with the subtraction strategies, more work with the number families and triangular flash cards is in order. Solving problems structured to automatically trigger a student to think of addition for subtraction would also be helpful. Once "think addition" is used reliably with sums to ten, the other options for solving subtraction facts with addition sums greater than ten can be revisited. Spend more time with manipulatives such as two ten frames when reteaching building up or back down through ten.

B. Reinforcing and Extending Learning

Students who have achieved or exceeded the outcomes will benefit from ongoing opportunities to apply and extend their learning. These activities should support students in developing a deeper understanding of the concept and should not progress to the outcomes in subsequent grades. If students are proficient using these strategies, challenge them to apply them to two-digit addition and subtraction. Can a student take a problem such as 23 + 48 and mentally alter it to 20 + 1 + 2 + 40 + 8 and by combining the 2 and 8, make a 10 to add to 20 + 40 for a total of 70 and the 1 left over from 3. When a student is asked 42 – 28, can they convert it to 42 – 30 = 12 and then add 2 more to compensate for giving an extra 2 to the 28 to make it 30? You may want to focus student thinking on relationships and patterns they already use with questions such as, "Is there any way that knowing the double 6 + 6 can help you solve mentally 16 + 6? What about 26 + 6? What about 36 + 6? Could you mentally solve 26 + 36?"