Mathematics · Year 1

Active learning ideas

Mass and Hefting

Active learning helps Year 1 students grasp mass because hefting objects builds intuitive understanding before formal tools. Hands-on comparisons with real materials make abstract ideas like size and density concrete and memorable.

• ACARA Content Descriptions
• AC9M1M01

• 20–35 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Plan-Do-Review
• 25 min · Pairs

Pairs Hefting Sort: Everyday Objects

Pairs gather 12 classroom items like erasers, books, and blocks. They heft each pair to decide heavier, lighter, or same, then sort into three piles. Groups share one surprise and explain using comparative language.

Explain why a bigger object doesn't always have more mass than a smaller one.

Facilitation Tip

During Pairs Hefting Sort, model how to lift objects with both hands and hold them steady to feel differences.

What to look for

Present students with two classroom objects (e.g., a book and a pencil case). Ask them to heft both objects and state which one is heavier and why, using comparative language.

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

Activity 02

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

Prediction Relay: Material Masses

In small groups, students view two hidden objects by material clues, predict which is heavier, then heft to check. Rotate roles for predictor, hefter, and recorder. Class discusses patterns in predictions.

Compare the mass of two objects using only your hands.

Facilitation Tip

In the Prediction Relay, circulate to listen for students’ reasoning about material and size, not just guesses.

What to look for

Place a large, hollow plastic ball and a small, solid metal ball on a table. Ask students: 'Which ball looks bigger? Which ball do you predict will be heavier? Why?' Then, have them heft both to compare and discuss their predictions.

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

Activity 03

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

Whole Class Mystery Weigh-Off

Display 10 paired objects on tables. Class votes on heavier via show of hands, then volunteers heft to reveal. Tally correct predictions and note why size misled some.

Predict which object will be heavier based on its material.

Facilitation Tip

For the Whole Class Mystery Weigh-Off, keep the focus on discussion rather than right answers to build comfort with uncertainty.

What to look for

Give each student a card with a picture of two objects (e.g., a feather and a rock). Ask them to write one sentence describing which object is lighter and one sentence explaining why size doesn't always mean heavier.

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

Activity 04

• Plan-Do-Review
• 20 min · Individual

Individual Mass Journal: Home Hunt

Students select five home objects, sketch them, predict relative masses, then heft and label heavier or lighter. Bring journals to share next lesson.

Explain why a bigger object doesn't always have more mass than a smaller one.

Facilitation Tip

In the Individual Mass Journal, provide sentence starters like 'I hefted ___, which felt ___ than ___.' to scaffold writing.

What to look for

Present students with two classroom objects (e.g., a book and a pencil case). Ask them to heft both objects and state which one is heavier and why, using comparative language.

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

A few notes on teaching this unit

Teachers approach mass by starting with what students can feel directly—lifting objects—before introducing vocabulary. Avoid rushing to standardized units; let students develop their own benchmarks through repetition. Research shows that peer discussion during hefting sharpens comparative judgments more than teacher-led explanations alone.

Successful learning shows when students use comparative language accurately, predict mass based on material, and discuss why bigger objects aren’t always heavier. Confidence in hefting grows through repeated, structured comparisons.

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Watch Out for These Misconceptions

• During Pairs Hefting Sort, watch for students who assume the larger object is always heavier.

  Ask pairs to lift both objects and state which one feels heavier first, then prompt them to explain why using their hands and eyes together.

• During Prediction Relay: Material Masses, watch for students who think all metal objects feel equally heavy.

  Have students heft metal keys of different sizes, then discuss how size affects mass even when material is the same. Ask, 'Why does a big key feel heavier than a small one?'

• During Whole Class Mystery Weigh-Off, watch for students who dismiss hefting as unreliable when objects feel close in mass.

  Guide students to lift objects multiple times with eyes closed, then compare notes with a partner to reach a consensus.

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Methods used in this brief

• Plan-Do-Review