Mathematics · Grade 2

Active learning ideas

Subtracting Two-Digit Numbers (With Regrouping)

Students learn best when they see, touch, and explain regrouping for themselves. When children physically exchange blocks or draw pictures, they connect abstract symbols to concrete meaning. This hands-on work turns a tricky step into a clear process they can own.

• Ontario Curriculum Expectations
• 2.NBT.B.5

• 15–35 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Plan-Do-Review
• 35 min · Small Groups

Manipulative Stations: Base-Ten Regrouping

Set up stations with base-ten blocks and problem cards like 53 - 28. Students build both numbers, exchange a ten rod for ten unit blocks when needed, subtract, and record steps. Rotate stations to try different problems.

Justify why we 'borrow' from the tens place when we don't have enough ones to subtract.

Facilitation Tip

During Model Building, provide sentence stems like ‘I regrouped because...’ to scaffold verbal explanations.

What to look for

Provide students with the problem 53 - 28. Ask them to solve the problem and then write one sentence explaining why they had to regroup from the tens place. Collect and review for understanding of the regrouping process.

• Remember
• Apply
• Analyze
• Self-Management
• Decision-Making
• Self-Awareness

Activity 02

• Plan-Do-Review
• 20 min · Pairs

Pair Whiteboard Explanations: Justify the Borrow

Partners use whiteboards to solve regrouping problems. One draws a model and explains the borrow; the other checks with addition. Switch roles after three problems and discuss strategies.

Construct a visual model to demonstrate regrouping when solving 42 - 17.

What to look for

Display the problem 61 - 35 on the board. Ask students to use base-ten blocks or draw a picture to show how they would regroup to solve it. Observe students' manipulation of blocks or drawings to assess their conceptual understanding.

• Remember
• Apply
• Analyze
• Self-Management
• Decision-Making
• Self-Awareness

Activity 03

• Plan-Do-Review
• 25 min · Whole Class

Relay Race: Subtraction Checks

Divide class into teams. First student solves a regrouping problem on the board, next adds back to verify, tagging the following teammate. First team to finish correctly wins.

Analyze the relationship between addition and subtraction when checking a subtraction answer.

What to look for

Pose the question: 'How can we use addition to check if our answer to 45 - 19 is correct?' Facilitate a class discussion where students explain how adding the difference (26) to the subtrahend (19) should result in the original minuend (45).

• Remember
• Apply
• Analyze
• Self-Management
• Decision-Making
• Self-Awareness

Activity 04

• Plan-Do-Review
• 15 min · Individual

Model Building: Individual Visuals

Students receive problems and draw or build base-ten models showing regrouping. Label steps like 'rename 1 ten as 10 ones' and check with addition equation.

Justify why we 'borrow' from the tens place when we don't have enough ones to subtract.

What to look for

Provide students with the problem 53 - 28. Ask them to solve the problem and then write one sentence explaining why they had to regroup from the tens place. Collect and review for understanding of the regrouping process.

• Remember
• Apply
• Analyze
• Self-Management
• Decision-Making
• Self-Awareness

A few notes on teaching this unit

Start with base-ten blocks so students experience the ‘not enough ones’ moment firsthand. Use expanded form to show that 3 tens 12 ones equals the original value, reinforcing that regrouping preserves the total. Avoid rushing to the algorithm; let the concrete model drive the abstract steps.

By the end of these activities, students will subtract two-digit numbers with regrouping confidently and explain each step aloud. They will justify why regrouping is needed and verify their work through addition, showing place-value understanding in both actions and words.

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Watch Out for These Misconceptions

• During Manipulative Stations, watch for students who regroup unnecessarily on every problem.

  Give them a mix of problems and ask them to sort them into two piles: ones that need regrouping and ones that do not. Discuss the pattern of when regrouping is required based on digit comparisons.

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Methods used in this brief

• Plan-Do-Review