Addition and Subtraction

Strand: Number
Outcome: 3

Step 3: Plan for Instruction

Guiding Questions

What learning opportunities and experiences should I provide to promote learning of the outcomes and permit students to demonstrate their learning?
What teaching strategies and resources should I use?
How will I meet the diverse learning needs of my students?

A. Assessing Prior Knowledge and Skills

Before introducing new material, consider ways to assess and build on the students' knowledge and skills related to counting.

Model the addition of 127 and 48 using concrete or visual representations and record the process symbolically.
Subtract 48 from 73 by modelling the subtraction using concrete or visual representations and record the process symbolically.
Create an addition or subtraction story problem for the number sentence:
33 – 18 = XX or 18 + XX = 33.
Determine the sum of 185 and 25 using a personal strategy and explain how the strategy works.
Subtract 39 from 278 using a personal strategy and explain how the strategy works.
Solve the following problems in more than one way using personal strategies and explaining how the strategies work:
- After receiving 16 hockey cards from a friend, Nicholas has a total of 135 hockey cards. How many hockey cards did he have before receiving some from his friend?
- Jimmy has 57 cents and Mary has 85 cents. Mary has how many more cents than Jimmy?

If a student appears to have difficulty with these tasks, consider further individual assessment, such as a structured interview, to determine the student's level of skill and understanding.

Sample Structured Interview: Assessing Prior Knowledge and Skills

B. Choosing Instructional Strategies

Consider the following general strategies for teaching.
Consider the following guidelines for teaching addition and subtraction:

Teach in a problem-solving context. Research shows that by solving problems using addition and subtraction, the students create personal strategies for computing and develop understanding about the relationship between the operations and their properties (NCTM 2000, p. 153).
Choose problems that relate to the children's own lives (Van de Walle 2001).
Provide a variety of problems representing the different addition and subtraction situations with varying degrees of difficulty to differentiate instruction.
Work with the whole group initially and have the students paraphrase the problem to enhance understanding (Willis et al. 2006) and to recognize which numbers in a problem refer to a part or to a whole.
Have the students estimate the answer to the problem before calculating so that they are better able to determine the reasonableness of their answers.
Have base ten materials available for the students to use as needed.
Provide time for the students to create their personal strategies to solve the problem and share these strategies with members of their group or with the entire class.
Guide the discussion by asking questions to encourage thinking about number relationships, the connection between addition and subtraction, and their personal strategies.
Have the students compare their answers to the estimates that they made before solving the problems.
Challenge the students to solve the problem another way, do a similar problem without models or clarify the explanation of their personal strategies.
Have the students critique their personal strategies as well as those of their classmates to decide which strategy works best for them and why.
Have the students create problems for a variety of number sentences illustrating addition and subtraction.

C. Choosing Learning Activities

The following learning activities are examples of activities that could be used to develop student understanding of the concepts identified in Step 1.

Sample Learning Activities
Teaching Personal Strategies for Adding and Subtracting	Download Activities
Teaching Estimating Sums and Differences	Download Activities
Teaching Solving Problems Involving Addition and Subtraction	Download Activities