Measuring Weight with Non-Standard Units

Active learning helps students grasp the abstract concept of weight by providing concrete, hands-on experiences that reveal weight relationships. Using non-standard units like blocks or hands makes the learning process tangible and memorable, while balance scales turn abstract comparisons into visible outcomes.

• 2nd Class
• Mathematical Explorers: Building Foundations
• 4 activities
• 25 min–45 min

Learning Objectives

1. Compare the weights of two classroom objects using a balance scale and identify which is heavier or lighter.
2. Order a set of three to five classroom objects from lightest to heaviest based on balance scale comparisons.
3. Explain how a balance scale indicates relative weight by showing which side is heavier.
4. Classify classroom objects into categories based on their relative weight (e.g., lighter than a pencil, heavier than a book).

Experiential Learning

⏱ 30 min·Pairs

Balance Scale Pairs: Object Showdown

Pair students and provide balance scales with everyday objects like erasers, books, and toys. Each pair compares two objects at a time, records which is heavier, and predicts outcomes before testing. Switch pairs after five comparisons to share findings.

Prepare & details

How can you use balance scales and everyday objects to compare the weights of things?

Facilitation Tip: During Balance Scale Pairs, circulate and ask guiding questions like, 'What do you notice about the tilt of the scale?' to encourage observation and reasoning.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 45 min·Whole Class

Whole Class Ordering Line: Heaviest to Lightest

Collect 10-12 classroom items and have the class use a large balance scale to compare them one by one. Students vote on predictions, test with the scale, and physically arrange items in a line from lightest to heaviest. Discuss surprises at the end.

Prepare & details

What does it mean for one object to be heavier or lighter than another?

Facilitation Tip: For Whole Class Ordering Line, model how to hold objects carefully and place them gently on the scale to avoid tipping errors.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 35 min·Small Groups

Non-Standard Unit Relay: Block Weighing

Divide into small groups with scales and unifix cubes as non-standard units. Groups select objects, find how many cubes balance each one, and create a class chart comparing results. Rotate roles for weighing and recording.

Prepare & details

Can you order a set of objects from lightest to heaviest using a balance scale?

Facilitation Tip: In Non-Standard Unit Relay, time the activity so students stay engaged and avoid rushing to finish before reflecting on their measurements.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Experiential Learning

⏱ 25 min·Individual

Individual Estimation Challenge: Secret Weights

Give each student a set of five hidden objects in bags. Students estimate order from lightest to heaviest, then verify with personal mini-scales and non-standard units like paper clips. Journal the matches and mismatches.

Prepare & details

How can you use balance scales and everyday objects to compare the weights of things?

Facilitation Tip: During the Individual Estimation Challenge, provide a quiet space for students to focus on their predictions before testing them on the scale.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Teaching This Topic

Teachers should emphasize the process of observation and reasoning over speed or correctness. Model how to use language like 'heavier than' and 'lighter than' consistently to build vocabulary. Avoid correcting misconceptions immediately; instead, let students discover inconsistencies through the balance scale’s feedback, then facilitate a class discussion to reconcile their findings. Research shows that hands-on comparisons with varied objects help students internalize weight relationships more deeply than abstract explanations alone.

What to Expect

By the end of these activities, students should confidently compare and order objects by weight, explain their reasoning using balance scales, and recognize that size does not always determine weight. They should also be able to articulate why different non-standard units can yield consistent results when measuring the same set of objects.

Watch Out for These Misconceptions

Common Misconception

During Balance Scale Pairs, watch for students assuming that the larger object will always tip the scale downward.

What to Teach Instead

Prompt students to test their assumption by placing the large balloon and small rock on the scale, then ask them to explain why the small rock is heavier despite its size. Use this moment to introduce the idea that weight depends on density and material, not just size.

Common Misconception

During Whole Class Ordering Line, watch for students thinking that the type of non-standard unit (e.g., blocks vs. hands) changes the actual weight of the objects.

What to Teach Instead

Have students measure the same object with different units (e.g., 5 blocks vs. 2 hands) and ask them to compare the results. Discuss how the unit changes but the order of objects remains consistent, reinforcing that weight is a property of the object, not the measurement tool.

Common Misconception

During Balance Scale Pairs, watch for students confusing the balance scale’s tilt with measuring length rather than weight.

What to Teach Instead

Ask students to trace the movement of the scale’s arms with their fingers as it tips and ask, 'What is moving here? What does that movement tell us?' Guide them to connect the downward tilt of the heavier side to the concept of weight pulling down, not length stretching out.

Assessment Ideas

Quick Check

After Balance Scale Pairs, provide each pair of students with three objects (e.g., a crayon, an eraser, a small toy car). Ask them to place two objects on the scale and state which is heavier. Then, ask them to order all three objects from lightest to heaviest and share their reasoning with the class.

Discussion Prompt

During Whole Class Ordering Line, present the scenario, 'Imagine you have a bag of feathers and a bag of rocks. Which bag is heavier? How do you know?' Facilitate a class discussion where students use the balance scale to test their ideas and explain their reasoning in pairs before sharing with the group.

Exit Ticket

After Non-Standard Unit Relay, give each student a card with two objects pictured (e.g., a book and a pencil). Ask them to draw a simple balance scale showing which object is heavier. Then, ask them to write one sentence explaining their drawing, using the term 'heavier' or 'lighter' correctly.

Extensions & Scaffolding

• For students who finish early, ask them to create a new object using classroom materials (e.g., a ball of clay) and compare its weight to their original set, recording their findings in a simple chart.
• For students who struggle, provide objects that feel distinctly different in weight (e.g., a feather and a book) to reinforce the concept of heavy versus light before introducing subtler differences.
• To explore further, challenge students to find three objects in the classroom that, when ordered by weight, create a pattern (e.g., lightest to heaviest in a repeating sequence).

Key Vocabulary

Weight	How heavy or light an object is. We compare weights to see which object has more or less of this.
Balance Scale	A tool with two pans that helps us compare the weights of two objects. If one side goes down, that object is heavier.
Heavier than	Describes an object that weighs more than another object. On a balance scale, it makes that side go down.
Lighter than	Describes an object that weighs less than another object. On a balance scale, it makes that side go up.
Equal weight	When two objects weigh the same amount. A balance scale will stay level when these objects are placed on its pans.