Mathematics · 1st Grade

Active learning ideas

Adding Multiples of Ten

Active learning works well for adding multiples of ten because students need to physically and visually see how the tens place changes while the ones stay the same. This hands-on approach builds a strong foundation in place value, making abstract ideas more concrete and easier to grasp.

• Common Core State Standards
• CCSS.Math.Content.1.NBT.C.4
• CCSS.Math.Content.1.NBT.C.5

• 15–25 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Inquiry Circle
• 20 min · Pairs

Inquiry Circle: What Changed?

Partners build a two-digit number with base-ten blocks, then add one rod (ten) at a time. After each addition, they record the new number and circle what changed. Groups compile results and share their pattern discovery with the class.

Explain how adding a multiple of ten only changes the tens digit.

Facilitation Tip

During Collaborative Investigation: What Changed?, circulate and ask guiding questions like 'What stayed the same in your rods and units?' to keep students focused on the key idea.

What to look for

Present students with a number line from 10 to 100. Ask them to mark where 45 would be, then circle 55, 65, and 75. Ask: 'What do you notice about the numbers you circled?'

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Activity 02

• Think-Pair-Share
• 15 min · Pairs

Think-Pair-Share: Predict the New Number

Announce a starting number (e.g., 34). Ask partners to predict what 34 + 20 will be before any calculation. Each partner shares their prediction and reasoning. The class tests predictions with a hundreds chart or base-ten blocks and discusses why the ones digit never moved.

Predict the outcome when adding 10, 20, or 30 to a given number.

Facilitation Tip

For Think-Pair-Share: Predict the New Number, provide sentence stems like 'I think the new number will be ____ because ____' to structure student responses.

What to look for

Give each student a card with a problem like '32 + 20 = ?'. After they solve it using drawings or mental math, ask them to write one sentence explaining how adding 20 changed the number 32.

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

Activity 03

• Gallery Walk
• 20 min · Small Groups

Gallery Walk: Hundreds Chart Hop

Post large hundreds charts around the room with a starting number circled. Students rotate and draw an arrow showing the result of adding a given multiple of ten (10, 20, or 30). They record the equation and explain in one sentence why the ones digit stayed the same.

Design a mental strategy for quickly adding multiples of ten.

Facilitation Tip

In Gallery Walk: Hundreds Chart Hop, place sticky notes with follow-up questions like 'How did moving down the chart affect your number?' near each station.

What to look for

Pose the question: 'If you have 57 cents and you find 3 more dimes, how much money do you have now? Explain your thinking.' Encourage students to share different strategies they used to solve the problem.

• Understand
• Apply
• Analyze
• Create
• Relationship Skills
• Social Awareness

Activity 04

• Stations Rotation
• 25 min · Small Groups

Stations Rotation: Mental Math Challenge

Each station provides a starting number and a multiple of ten to add (presented with blocks, a hundreds chart, and numerals only). Students solve mentally at the numeral station and explain their strategy, building toward fluent mental addition of multiples of ten.

Explain how adding a multiple of ten only changes the tens digit.

Facilitation Tip

During Station Rotation: Mental Math Challenge, listen for students using skip-counting or place value talk to solve problems, not counting by ones.

What to look for

Present students with a number line from 10 to 100. Ask them to mark where 45 would be, then circle 55, 65, and 75. Ask: 'What do you notice about the numbers you circled?'

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

A few notes on teaching this unit

Teach this topic by first using manipulatives like base-ten rods and units so students see the physical change in the tens place while the ones remain unchanged. Model think-alouds to verbalize the process, then gradually move to mental math and abstract representations. Avoid rushing to written algorithms before students understand the place value shift. Research shows that students who visualize the hundreds chart or number line develop stronger mental math strategies for adding tens.

Successful learning looks like students confidently adding multiples of ten without counting by ones, explaining why only the tens digit changes, and using place value language to describe their process. They should also transfer this skill to real-world contexts like money or number lines.

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Watch Out for These Misconceptions

• During Collaborative Investigation: What Changed?, watch for students who change both digits when adding tens.

  Have students use base-ten rods and units to physically add only rods while keeping the units in place, then ask them to describe what they observe about the ones digit.

• During Station Rotation: Mental Math Challenge, watch for students who count by ones to add a multiple of ten.

  Guide students to use the skip-count-by-tens sequence on the hundreds chart or number line to build a mental framework for efficient computation.

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Methods used in this brief

• Inquiry Circle
• Think-Pair-Share
• Gallery Walk
• Stations Rotation