Comparing by Mass

Curriculum Reference

Mathematics – Year 1
AC9M1M01 – Compare directly and indirectly and order objects and events using attributes of length, mass, capacity and duration, communicating reasoning.

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Lesson Duration

60 minutes

Learning Intentions (LI)

We are learning to compare and order objects according to mass and justify our reasoning.

Success Criteria (SC)

• I can compare and order objects according to mass.
• I can justify my reasoning using correct mathematical vocabulary.

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Vocabulary Focus

• Mass
• Weight
• Heaviest
• Lightest
• Compare
• Order
• Scales

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Materials Required

• A balance scale (1 per pair of students)
• A digital scale (for demonstration)
• Classroom objects: books, erasers, blocks, balls, scissors, glue sticks, feathers, toy animals, etc.
• Printable recording sheets for comparison results
• "Mass Detective" outdoor challenge cards
• Whiteboards and markers
• Clipboards
• Paper for drawing scales
• Chart paper for whole-class Venn Diagram on object weights
• Timer/stopwatch (for timed activities)

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Differentiated Activity Tiers

Aligned with student ability and understanding:

⭐️⭐️⭐️ 3 Star Learners

Focus: Direct Comparison Using Hands-On Materials

• Begin by introducing vocabulary with visual aids and movement-based explanations.
  E.g. Invite students to lift one backpack with both hands and describe its mass.
• Teacher-led discussion: “What is mass?”
• Model how to use a balance scale. Show how one side goes down if the object is heavier.
• Students work in pairs using balance scales to compare classroom items.
  Guiding Questions:
  • Which is heavier?
  • Which is lighter?
• Record results in pairs on visual chart sheets.
• Wrap this section with students describing findings in pairs using sentence starters:

  “The glue stick is heavier than the crayon because the scale tipped to that side.”

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⭐️⭐️⭐️⭐️ 4 Star Learners

Focus: Ordering and Indirect Comparing

• Extend the comparison to placing objects in order from lightest to heaviest.
• Introduce challenge: Compare three objects without placing them all on the scales at once.
• Students work in triads and rotate through stations with new object sets.
  Open-ended question to deepen inquiry:
• "How can you work out which object is the heaviest without using the scale each time?"
• Encourage students to use prior comparisons to indirectly order.
  E.g. If Block A is heavier than Block B, and Block B is heavier than Block C, what can we say about A and C?
• Use outdoor learning: students complete a “weight walk” in the schoolyard, using challenge cards (e.g. “Find two natural items and tell which one is heavier and why”).

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⭐️⭐️⭐️⭐️⭐️ 5 Star Learners

Focus: Deep Reasoning and Scale Diagrams

• Discuss: “What happens to a scale if one item is heavier?”
• Demonstrate equal weight using the digital scale to confirm balance scenarios.
• Students hypothesise about how the scale will behave before testing.
• Have students draw scales showing which object is heavier and use arrow symbols to show direction of movement.
  E.g. ✧Image of scale with blocks, down arrow on heavy side✧
• Students explain their scale diagrams to a peer using full sentences and vocabulary.
• Mini challenge: Show students a drawn balance scale and ask them to explain what must be happening between the two items to cause that image.

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Warm-Up (10 minutes)

Mass Warm-Up Game – “Guess It!”

• Pass around a mystery box. Students guess if it's light or heavy.
• Why do they think that? Introduce idea of justification using clues like how it feels, how it moves.

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Whole Class Input (10 minutes)

• Anchor chart creation: collaboratively build definitions and examples for vocabulary (mass, heaviest, lightest).
• Add real objects next to each word with velcro or blue-tack for visual anchor.
• Teacher models comparisons using exaggerated expressions and balance scale to make learning memorable.

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Rotational Activities (30 minutes)

Students rotate through three zones every 10 minutes (mixed-ability grouping):

1. Hands-On Comparison Zone

Compare 2–3 everyday classroom items using balance scales. Record results on clipboards. Includes some trickier objects like a scrunched-up paper vs. a sponge.

2. Mass Detective Outdoor Challenge

In the playground, students pick two natural items (leaf, rock, stick, etc.), write or draw them, and predict which is heavier. Then test with a balance scale outside.

3. Draw and Explain Zone

Draw your own balance scale and place two imaginary or real objects on each side. Use arrows and labels to tell which is heavier and why. Discuss with a peer.

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Conclusion (10 minutes)

Mathematical Circle Time

• Gather in a circle. Invite volunteers to share something surprising they learnt.
• Ask:

  “Did you ever guess wrong? Why do you think that happened?”
  “How can you prove something is heavier?”

• Reflect on LI and SC as a group.
• Use thumbs up/side/down as a quick check on how confident students feel in comparing mass.

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Assessment Opportunities

✔ Observations during group tasks (using a checklist focused on SCs)
✔ Recording sheets from comparison tasks
✔ Drawn scale diagrams as evidence of understanding
✔ Oral explanation during group discussion
✔ Teacher anecdotal notes on mathematical language usage

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Extension Opportunities

• Introduce non-standard units (e.g. “How many counters does this pencil weigh?”)
• Ask students to write a story or comic about two animals comparing who is heavier and how they find out
• Invite students to find an item at home and bring in a drawing of how they’ve compared its mass with something else

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Adjustments and Inclusion

• Provide visual prompts for EAL/D learners (e.g. concrete examples with labels)
• Use adaptive scissors, larger items or lighter objects where fine motor or strength support is needed
• Allow oral recordings instead of written responses for students requiring literacy differentiation
• Use peer buddies for reading outdoor challenge cards aloud

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Teacher Reflection Prompts

• Did students use the correct vocabulary independently?
• Which comparison method (direct/indirect) did they grasp better?
• How did working in the outdoor environment impact engagement?
• Which students demonstrated deep reasoning through their scale diagrams?

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Wow Factor 🌟

• Bringing maths outside with a detective twist
• Students drawing scale diagrams like real mathematicians
• High use of student explanation, prediction and inquiry
• Accessible multiple levels of entry with challenge built in

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📘 “Mathematics begins not with numbers, but with noticing.” — This lesson lets Year 1 students explore comparing mass in a playful, scientific and rigorous way.