# Addition and Subtraction

**Strand:** Number

**Outcome:** 3

## 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

The students who have difficulty solving addition or subtraction problems by estimating and by using a personal strategy will enjoy more success if one-on-one time is provided. This time will allow for open communication to diagnose where the learning difficulties lie. Assessment by observing a student solving problems will provide valuable data to guide further instruction. Success in problem solving depends on a positive climate in which the students are confident in taking risks. By building on the understanding that each student already has and accommodating the individual learning styles, success will follow.

If the difficulty lies in understanding the problem, use the following strategies:

- provide problems that relate to the student's interest; use the student's name in the problem
- use smaller numbers in the problem initially
- have the student paraphrase the problem
- guide the student to determine if the numbers refer to a part or a whole
- ask the student if the unknown in the problem refers to a part of a whole
- provide base ten materials for the students to represent the problem as needed
- have the student decide which operation should be used and why
- ask guiding questions to show the connections between addition and subtraction and the possible option of using either operation
- provide a graphic organizer, such as the K–N–W–S chart (see Blackline Master).

If the difficulty lies in estimating sums and differences, use the following strategies:

- use the base ten materials to focus on the place values of the numbers and the relationship among the place values
- use smaller numbers initially and connect them to larger numbers; e.g., connect 30 to 300 to 3000
- convince the student of the need for estimating by citing many real-world examples of where estimating is needed
- review number facts and place value
- emphasize flexibility in estimating, capitalizing on the student's methods and fine tuning them for correctness and efficiency
- take small steps using the front-end strategy without compensation first, and then adding the compensation when the student sees the need for it in providing a better estimate.

If the difficulty lies in using personal strategies to solve addition and subtraction problems, use the following strategies:

- use smaller numbers in the problems initially
- review place value and number facts
- provide base ten materials as needed
- think aloud a personal strategy that you would use to solve the problem and explain why this strategy is more efficient than another one that you describe
- emphasize flexibility in choosing a personal strategy; a strategy that is efficient for one student may not be efficient for another student
- build on the student's understanding of place value and number facts to guide him or her in finding a strategy that works
- provide ample time for the students to think and ask questions to clarify thinking
- have the students work in groups so that they learn strategies from one another
- guide the students to critique various personal strategies to find one that can be used on a variety of problems efficiently
- have the students explain their personal strategies to the class so others can hear how they work in 'kid' language
- post various personal strategies in the classroom for the students to share and critique
- encourage the student to check the reasonableness of the answer using a given personal strategy by comparing the answer to the estimated answer provided earlier.

### B. Reinforcing and Extending Learning

The students who have achieved or exceeded the outcomes will benefit from ongoing opportunities to apply and extend their learning. These activities should support the students in developing a deeper understanding of the concept and should not progress to the outcomes in subsequent grades.

Consider strategies, such as the following.

- Provide tips for parents on practising adding and subtracting at home or in the community. For example:
- take the children shopping and have them estimate the total grocery bill prior to going through the check out
- collect the cash register receipts, cover the total, and have the children estimate the total; or, tear off the totals and have the children match the receipts with the correct totals, using estimation
- talk to your children about data in the newspaper and magazines, and encourage them to add and subtract mentally and explain how they are doing it.

- Have the students create problems showing the various types of addition and subtraction problems (change, part–part–whole, and comparison) and write appropriate number sentences for each one. These problems can be displayed in the chart on the bulletin board.
- Have the students create problems with different contexts but using the same numbers, such as 259 and 160. They could follow this up by having the class decide which of the problems could be solved using a given number sentence, such as 259 – 160 = XX.
- Have the students convert single-step addition or subtraction problems into multistep problems and explain to other students how to solve them.
- Have the students critique other students' personal strategies and explain why they work or not. Which would be the most efficient and why?
- Have the students write an explanation for a personal strategy so that everyone in the class can understand it.
- Have the students compare the operations of addition and subtraction by discussing the commutative property (order property) and the zero property as well as other characteristics related to these two operations.