Measurement of Weight: Non-Standard Units

Active learning helps students grasp that weight is not just about how big something looks. When children handle objects and measure them with non-standard units, they directly experience how mass, not size alone, determines balance. This hands-on approach makes abstract ideas concrete and memorable for young learners.

• Class 3
• Mathematics
• 4 activities
• 25 min–45 min

Learning Objectives

1. Compare the weights of two objects using a balance scale and non-standard units.
2. Explain why measurements using different non-standard units can yield different results.
3. Construct a simple balance scale to demonstrate weight comparison.
4. Identify situations in daily life where comparing weights is important.

Collaborative Problem-Solving

⏱ 35 min·Pairs

DIY Balance Scale Construction

Provide rulers, strings, and plastic cups for students to build balances. In pairs, they test objects like erasers and chalk pieces, noting how many marbles balance each. Pairs share results and discuss surprises.

Prepare & details

Explain why non-standard units can be inconsistent for measuring weight.

Facilitation Tip: During DIY Balance Scale Construction, remind groups to tie the string tightly so the ruler stays balanced in the middle.

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 45 min·Small Groups

Object Weighing Stations

Set up stations with non-standard units: blocks for books, marbles for fruits, pencils for bags. Small groups rotate, measure three objects per station, and record counts on charts. Conclude with class comparison.

Prepare & details

Construct a balance scale to compare the weight of two objects.

Facilitation Tip: At Object Weighing Stations, circulate and ask guiding questions like, 'Why do you think the pebble needed more beads than the eraser?'

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 30 min·Small Groups

Weight Sorting Relay

Divide class into teams. Each team sorts classroom items into 'light', 'medium', and 'heavy' piles using hand balances and blocks. Teams verify by balancing against standards and explain choices.

Prepare & details

Analyze real-world situations where comparing weights is essential.

Facilitation Tip: For Weight Sorting Relay, pair students so they can discuss their reasoning before placing objects in order.

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 25 min·Individual

Real-Life Weighing Hunt

Students hunt for pairs of objects around the classroom that balance with the same number of erasers. Individually record pairs and units used, then verify in whole class discussion.

Prepare & details

Explain why non-standard units can be inconsistent for measuring weight.

Facilitation Tip: During Real-Life Weighing Hunt, provide a checklist to keep students focused on finding objects of varied weights.

Setup: Flexible seating that allows clusters of 5-6 students; desks can be grouped in rows of three facing each other if fixed furniture limits rearrangement. Wall or board space for displaying group norm charts and the session agenda is helpful.

Materials: Printed problem brief cards (one per group), Role cards: Facilitator, Questioner, Recorder, Devil's Advocate, Communicator, Group norm chart (printable poster format), Individual reflection sheet and exit ticket, Timer visible to the class (board countdown or projected timer)

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Teaching This Topic

Teachers should let students explore first before explaining, as this builds curiosity and ownership of learning. Avoid rushing to correct misconceptions; instead, use the activities as evidence to guide discussions. Research shows that peer collaboration and immediate feedback during hands-on tasks strengthen conceptual understanding.

What to Expect

By the end of these activities, students will confidently compare weights using non-standard units and explain why a small heavy object can outweigh a large light one. They will also recognise that measurement results depend on the choice of unit and discuss how standardisation helps.

Watch Out for These Misconceptions

Common Misconception

During DIY Balance Scale Construction, watch for students who assume the larger object is heavier simply because it takes up more space.

What to Teach Instead

Ask them to balance a small stone against a large sponge using their scale. Then, have them replace the sponge with a smaller stone of the same material to observe how weight shifts with mass.

Common Misconception

During Object Weighing Stations, watch for students who believe non-standard units always give identical results for the same object.

What to Teach Instead

Have them measure the same book using marbles and then pebbles. Guide them to compare counts and discuss why differences occur, linking this to the need for standard units.

Common Misconception

During Real-Life Weighing Hunt, watch for students who confuse weight with size or volume.

What to Teach Instead

Provide a feather and a pebble, and ask them to predict which will balance more marbles. After measuring, have them describe what the activity revealed about weight versus appearance.

Assessment Ideas

Quick Check

After DIY Balance Scale Construction, present students with a small stone and a large eraser. Ask them to predict which is heavier, then provide beads and the scale to measure and record their findings. Listen for explanations that mention mass over size.

Discussion Prompt

During Object Weighing Stations, ask students, 'If you measure the same book with marbles and your friend measures it with pebbles, will you get the same number? Why or why not?' Note if they explain that unit size affects the count.

Exit Ticket

After Weight Sorting Relay, give each student a drawing of a balance scale with 3 blocks on one side and 1 toy car on the other. Ask them to circle the heavier side and write one sentence explaining their choice, focusing on the number of units used.

Extensions & Scaffolding

• Challenge students to find three objects that weigh the same as five marbles, then record their findings in a table.
• For students who struggle, provide pre-measured sets of objects and non-standard units to reduce cognitive load during comparisons.
• Deeper exploration: Ask students to design their own non-standard unit, measure an object, and explain why their unit works (or doesn’t) for consistency.

Key Vocabulary

Weight	How heavy an object is. We compare weights to see which object is heavier or lighter.
Non-standard units	Objects used for measuring that are not official units like kilograms or grams. Examples include marbles, blocks, or pebbles.
Balance scale	A tool used to compare the weights of two objects. When both sides are equal, the scale balances.
Heavier	Describes an object that has more weight than another object.
Lighter	Describes an object that has less weight than another object.