Solving 1-Step Word Problems (Addition and Subtraction)

Active learning engages students by connecting abstract numbers to real-world contexts, which is essential for solving word problems. Movement, discussion, and hands-on modeling help cement understanding of when to add or subtract, building confidence and fluency beyond rote number facts.

• Primary 3
• Mathematics
• 4 activities
• 25 min–45 min

Learning Objectives

1. Calculate the sum or difference in one-step word problems involving numbers up to 10,000.
2. Identify keywords and phrases in word problems that indicate whether to use addition or subtraction.
3. Represent the structure of a one-step word problem using a bar model.
4. Explain the steps taken to solve a one-step addition or subtraction word problem.
5. Verify the reasonableness of a calculated answer within the context of a word problem.

Problem-Based Learning

⏱ 30 min·Pairs

Pairs: Bar Model Matching

Provide cards with word problems on one set and blank bar models on another. Pairs match problems to models, draw the bars, and solve. They then swap with another pair to check and discuss differences.

Prepare & details

What key words or phrases in a problem tell you whether to add or subtract?

Facilitation Tip: For Individual: Real-Life Story Creator, remind students to include a question mark in their stories to signal the math problem they intend to solve.

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Problem-Based Learning

⏱ 45 min·Small Groups

Small Groups: Problem Sort and Solve

Prepare word problem cards sorted by addition or subtraction. Groups sort them into categories, justify choices with key words, draw models, and solve two from each pile. Share one solution as a group.

Prepare & details

How does drawing a model help you understand what a problem is asking?

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Problem-Based Learning

⏱ 35 min·Whole Class

Whole Class: Error Detective Game

Display a solved word problem with intentional errors. Class votes on correctness, then discusses evidence using models and context checks. Repeat with student-generated problems.

Prepare & details

How do you check that your answer makes sense in the context of the problem?

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Problem-Based Learning

⏱ 25 min·Individual

Individual: Real-Life Story Creator

Students write their own one-step word problem based on a classroom scenario, draw a model, solve it, and check sense. Collect and use select ones for next lesson.

Prepare & details

What key words or phrases in a problem tell you whether to add or subtract?

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Teaching This Topic

Teach students to pause after reading a problem and ask themselves, 'What is happening here?' This prevents automatic keyword responses. Use think-alouds to model uncertainty, showing how to test operations by building bar models and checking if the numbers make sense in context. Avoid rushing to answers; let confusion surface so misconceptions can be addressed early.

What to Expect

Students will confidently identify operations from word problems, use bar models to represent quantities, and explain their reasoning clearly. Peer feedback and error analysis become part of their problem-solving routine, not just final answers.

Watch Out for These Misconceptions

Common Misconception

During Pairs: Bar Model Matching, watch for students who automatically add when they see 'more' or subtract when they see 'less.'

What to Teach Instead

Have students highlight the action in the problem first, then build two bar models: one for addition and one for subtraction. Discuss which model matches the story before settling on an operation.

Common Misconception

During Small Groups: Problem Sort and Solve, watch for students who skip checking if their answer fits the problem context.

What to Teach Instead

Ask each group to write a sentence explaining why their answer makes sense in the problem, using the numbers in their explanation. Post one example on the board as a model.

Common Misconception

During Whole Class: Error Detective Game, watch for students who think bar models are only for addition.

What to Teach Instead

Provide subtraction problems with models showing a whole and a part removed. Have students physically cover the removed part with paper to see how the whole changes.

Assessment Ideas

Quick Check

After Pairs: Bar Model Matching, present a problem like 'The library had 4,200 books. They received 850 new books. How many books are there now?' Ask students to whisper the operation and answer to a partner before showing it on the board.

Exit Ticket

After Whole Class: Error Detective Game, give each student a problem card with an intentional error (e.g., added instead of subtracted). Ask them to correct it and explain their reasoning in one sentence.

Discussion Prompt

During Small Groups: Problem Sort and Solve, pose this prompt: 'A farmer picked 6,000 apples. He sold 2,300 apples. How many apples are left?' Ask groups to discuss whether the operation is addition or subtraction and why, then share their models with the class.

Extensions & Scaffolding

• Challenge early finishers to create a two-step version of their story, then swap with a partner to solve.
• Scaffolding for struggling students: provide problems with smaller numbers (up to 1,000) and allow the use of counters or blocks to model the problem.
• Deeper exploration: introduce problems with irrelevant information, then discuss which numbers matter and why.

Key Vocabulary

altogether	This word often signals that you need to combine quantities, meaning you should add.
difference	This word indicates that you need to find out how much more one quantity is than another, requiring subtraction.
bar model	A visual representation using rectangles to show the relationship between quantities in a word problem, helping to determine the operation needed.
keywords	Specific words or phrases in a word problem that provide clues about the mathematical operation to use, such as 'more than' or 'left'.
sum	The result when two or more numbers are added together.
remainder	The amount left over after performing a subtraction, often indicated by words like 'left' or 'remaining'.