Mathematics · Grade 2

Active learning ideas

Subtracting Two-Digit Numbers (No Regrouping)

Active learning works because subtracting two-digit numbers without regrouping requires students to see tens and ones as distinct units. Hands-on tools like base ten blocks and number lines make this abstract concept concrete, helping learners build strong place value foundations before moving to mental strategies.

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

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

Activity 01

• Stations Rotation
• 45 min · Small Groups

Stations Rotation: Place Value Subtraction

Prepare stations with base ten blocks, number lines, expanded form worksheets, and dry-erase boards. Students solve three problems at each station, like 64 - 21, recording strategies. Rotate groups every 10 minutes and share one insight as a class.

Explain how subtracting tens and ones separately helps solve a subtraction problem.

Facilitation Tip

During Station Rotation: Place Value Subtraction, set a timer for each station and provide a checklist so students practice all methods within the time frame.

What to look for

Provide students with the problem 67 - 24. Ask them to solve it using one strategy (base ten blocks, expanded form, or number line) and write one sentence explaining their chosen strategy.

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

Activity 02

• Stations Rotation
• 30 min · Pairs

Partner Number Line Jumps

Pairs draw a giant floor number line from 0 to 100 with tape. One student starts at the minuend, like 58, and jumps back tens then ones for the subtrahend, 23. Switch roles for three problems and discuss efficiency.

Design a number line strategy to solve 58 - 23.

Facilitation Tip

For Partner Number Line Jumps, have students alternate turns jumping and recording to ensure both partners participate actively.

What to look for

Present students with a set of subtraction problems without regrouping, such as 59 - 13 and 88 - 45. Ask them to solve two problems using expanded form and two problems using base ten blocks, recording their work.

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

Activity 03

• Stations Rotation
• 25 min · Small Groups

Block Busting Game

In small groups, students use base ten blocks to model a two-digit number. Partner announces a subtrahend without regrouping, like 45 - 12. Remove blocks by place value and verify the difference. Play five rounds.

Compare subtracting with base ten blocks to subtracting using expanded form.

Facilitation Tip

In the Block Busting Game, use a small whiteboard at each station for students to write their final answers before moving on.

What to look for

Pose the question: 'How is subtracting 50 from 70 similar to subtracting 5 from 7 when solving 75 - 23?' Facilitate a class discussion focusing on the role of place value in the subtraction process.

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

Activity 04

• Stations Rotation
• 20 min · Pairs

Expanded Form Match-Up

Create cards with problems, expanded forms, and answers. Students work individually or in pairs to match sets, such as 73 - 24 to (70 + 3) - (20 + 4) = 49. Discuss matches whole class.

Explain how subtracting tens and ones separately helps solve a subtraction problem.

Facilitation Tip

During Expanded Form Match-Up, include a self-check step where students verify their answers against a key before moving to the next set.

What to look for

Provide students with the problem 67 - 24. Ask them to solve it using one strategy (base ten blocks, expanded form, or number line) and write one sentence explaining their chosen strategy.

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

A few notes on teaching this unit

Teach this topic by starting with physical models such as base ten blocks to build understanding of place value. Avoid rushing students to mental math before they can explain their process with tools. Research shows that students who practice with manipulatives before abstract methods develop stronger number sense and fewer errors. Model think-alouds to demonstrate how to separate tens and ones, and encourage students to do the same during partner work.

Successful learning looks like students confidently breaking numbers into tens and ones, using models to subtract accurately, and explaining their steps with clear place value language. You will notice students moving from counting by ones to using efficient strategies with speed and accuracy.

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Watch Out for These Misconceptions

• During Station Rotation: Place Value Subtraction, watch for students counting back by ones on base ten blocks instead of removing groups of tens and ones.

  Redirect these students by modeling how to physically remove ten-blocks first, then ones-blocks, and count what remains. Ask them to explain how this matches the written equation.

• During Expanded Form Match-Up, watch for students subtracting the ones from the total without separating the expanded values.

  Have these students use a place value chart to align the expanded form with the original number, then subtract tens from tens and ones from ones before combining results.

• During Partner Number Line Jumps, watch for students using addition to find differences instead of subtracting the whole number.

  Ask them to start at the larger number and jump backward in equal steps, counting each jump aloud to reinforce the subtraction process.

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Methods used in this brief

• Stations Rotation