Mathematics · Primary 1

Active learning ideas

Subtraction without Regrouping (within 100)

Active learning works well for subtraction without regrouping because students need to see the concrete separation of tens and ones to build place value understanding. Hands-on manipulatives and games help them practice column subtraction while reinforcing that each digit is treated individually during subtraction without borrowing.

• MOE Syllabus Outcomes
• MOE: N(v).3
• MOE: N(v).4

• 20–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 30 min · Pairs

Manipulatives: Base-10 Block Subtraction

Provide base-10 blocks and place value mats. Students build two-digit numbers, remove blocks for the subtrahend starting with ones, then tens, and record the difference. Pairs verify by rebuilding and adding back.

How do we subtract ones from ones and tens from tens?

Facilitation Tip

During Base-10 Block Subtraction, circulate to ensure students physically remove the correct number of blocks from each place value group.

What to look for

Present students with a worksheet containing 5 subtraction problems without regrouping (e.g., 57 - 23, 89 - 41). Ask them to solve each problem and write one sentence explaining how they subtracted the ones digits.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Simulation Game
• 20 min · Pairs

Simulation Game: Subtraction Card War

Pairs draw two cards to form two-digit numbers where no regrouping is needed. The player with the larger number subtracts; correct answer wins both cards. Switch roles after each round.

When is it possible to subtract without regrouping?

Facilitation Tip

In Subtraction Card War, model the subtraction steps aloud as you play a round to reinforce the process.

What to look for

Give each student a card with a subtraction problem, such as '48 - 15'. Ask them to solve it and then write the addition problem that checks their answer. Collect these to gauge understanding of both subtraction and checking.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 03

• Stations Rotation
• 45 min · Small Groups

Stations Rotation: Multi-Modal Subtraction

Set up three stations: draw place value charts to subtract, jump on floor number lines, solve word problems with counters. Small groups rotate every 10 minutes, sharing one insight per station.

How does addition help us check our subtraction answer?

Facilitation Tip

At the Multi-Modal Subtraction stations, provide sentence stems for students to verbalize their subtraction steps.

What to look for

Ask students: 'When is it okay to subtract the ones from the ones and the tens from the tens without needing to borrow? How do you know?' Listen for explanations that reference the ones digit of the top number being larger than or equal to the ones digit of the bottom number.

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Activity 04

• Experiential Learning
• 25 min · Whole Class

Relay: Whole Class Problem Solving

Project a subtraction problem. Teams line up; first student subtracts ones on board, next does tens, last checks with addition. Correct team sits; continue with new problems.

How do we subtract ones from ones and tens from tens?

Facilitation Tip

For the Whole Class Problem Solving relay, assign roles to keep students engaged and accountable for each step.

What to look for

Present students with a worksheet containing 5 subtraction problems without regrouping (e.g., 57 - 23, 89 - 41). Ask them to solve each problem and write one sentence explaining how they subtracted the ones digits.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

A few notes on teaching this unit

Teach subtraction without regrouping by starting with concrete manipulatives to build place value understanding before moving to abstract symbols. Avoid rushing to procedural steps without ensuring students grasp the why behind subtracting ones from ones and tens from tens. Research shows that students who verbalize their steps during practice retain the concept longer.

Students should confidently separate numbers into tens and ones, subtract each place value, and check their answers using addition. They should explain their steps clearly and recognize when regrouping is not needed in subtraction problems.

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Watch Out for These Misconceptions

• During Base-10 Block Subtraction, watch for students removing blocks from tens to subtract ones or combining place values incorrectly.

  Prompt them to model the problem with blocks first, then write the column subtraction next to it. Ask, 'Where are your tens? Where are your ones? How do you subtract them separately?'

• During Subtraction Card War, watch for students subtracting the smaller number from the larger number regardless of place value order.

  Remind them to always subtract the bottom card from the top card and write the problem vertically. Model a round where you say, 'I have 5 tens and 2 ones minus 3 tens and 4 ones,' to reinforce place value order.

• During Multi-Modal Subtraction stations, watch for students skipping the check step with addition entirely.

  Provide a sentence strip prompt at each station: 'To check my answer, I will add _____ + _____ to see if it equals _____.' Circulate to ensure they complete this step.

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Methods used in this brief

• Experiential Learning
• Simulation Game
• Stations Rotation