Measuring Mass with Non-Standard Units

Active learning helps Primary 1 students grasp the abstract concept of mass by making it tangible. When children manipulate balance scales and count non-standard units, they build a concrete understanding of balance and measurement, which supports later work with standard units. This hands-on approach addresses common misconceptions early by letting students test ideas through trial and error.

• Primary 1
• Mathematics
• 4 activities
• 20 min–45 min

Learning Objectives

1. Compare the mass of two objects using a balance scale and non-standard units.
2. Explain why identical non-standard units are necessary for accurate mass comparison.
3. Record mass measurements using tally marks or simple number notation.
4. Classify objects into groups based on their measured mass relative to a standard unit.

Stations Rotation

⏱ 45 min·Small Groups

Stations Rotation: Balance Scale Challenges

Prepare four stations with balance scales, unit sets (cubes or clips), and objects like erasers, books, toys. Groups measure two objects per station, record units in notebooks, and predict next. Rotate every 10 minutes, then share findings.

Prepare & details

How do we use non-standard units to measure mass?

Facilitation Tip: During Station Rotation, circulate to each group and ask guiding questions like, 'Why did you choose those counters instead of buttons?' to prompt reflection.

Setup: Tables/desks arranged in 4-6 distinct stations around room

Materials: Station instruction cards, Different materials per station, Rotation timer

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

Experiential Learning

⏱ 25 min·Pairs

Prediction Pairs: Mass Guessing Game

Pairs select objects, predict unit count needed to balance, then test on shared scale. They record prediction versus actual, discuss differences. Extend by comparing two objects.

Prepare & details

Why must all the non-standard units have the same mass?

Facilitation Tip: For Prediction Pairs, have students explain their guesses before testing so peers can hear different reasoning strategies.

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·Whole Class

Whole Class: Mass Comparison Chart

Display objects; class votes predictions, then measures together using scale and units. Record on shared chart, discuss heaviest and lightest. Vote on most surprising result.

Prepare & details

How can we record and compare our measurements?

Facilitation Tip: In Whole Class Mass Comparison, invite students to present their findings on the chart to build collective understanding and vocabulary.

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

⏱ 20 min·Individual

Individual: Unit Hunt and Measure

Students find classroom items, choose units, measure mass alone, then verify with partner. Record in personal log with drawings.

Prepare & details

How do we use non-standard units to measure mass?

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

Teaching mass with non-standard units works best when students first explore freely before formal recording. Avoid rushing to vocabulary like 'mass' or 'balance'; let children describe what they notice first. Research shows that repeated trials with immediate feedback help correct misconceptions faster than explanations alone. Model curiosity by asking, 'What happens if we try this again with different units?' to encourage flexible thinking.

What to Expect

Students will demonstrate understanding by accurately balancing objects with non-standard units and recording their counts. They will explain why consistent units matter and compare masses using clear evidence from their balance tests. By the end of the lessons, they should confidently state whether one object is heavier based on unit counts, not size.

Watch Out for These Misconceptions

Common Misconception

During Station Rotation: Balance Scale Challenges, watch for students assuming all large objects are heavier. Redirect by asking them to balance a large balloon against a small pebble, then discuss observations in pairs to refine their understanding.

What to Teach Instead

During Station Rotation: Balance Scale Challenges, provide a large, light object and a small, heavy object. Have students balance them and note the counter counts, then discuss why size does not determine mass.

Common Misconception

During Station Rotation: Balance Scale Challenges, watch for students using mixed non-standard units without realizing it affects accuracy. Redirect by having them test with identical units and observe imbalances when units vary.

What to Teach Instead

During Station Rotation: Balance Scale Challenges, give mixed unit sets and ask groups to test and note imbalances. Guide them to see that consistent unit mass is essential for fair measurement.

Common Misconception

During Prediction Pairs: Mass Guessing Game, watch for students linking fewer units to a heavier object. Redirect by measuring familiar objects like apples versus feathers and charting results to clarify the inverse relationship.

What to Teach Instead

During Prediction Pairs: Mass Guessing Game, measure an apple and a feather using counters. Have students predict and test, then chart results to show that fewer units can mean a heavier object if the units are light.

Assessment Ideas

Quick Check

After Station Rotation: Balance Scale Challenges, provide students with a balance scale, a set of counters, and two different small objects. Ask them to predict which is heavier, use counters to balance each, and record the counts. Observe whether they use consistent units and record results accurately.

Exit Ticket

During Whole Class: Mass Comparison Chart, give each student a card with a drawing of a balance scale. One pan shows 5 blocks, the other shows 3 blocks. Ask students to draw more blocks on the lighter side to balance the scale and write the total number of blocks on each side.

Discussion Prompt

After Unit Hunt and Measure, present two different non-standard units, such as large buttons and small beads. Ask students whether measuring the same book with buttons and then with beads would yield the same number. Have them discuss why unit consistency matters in measurement.

Extensions & Scaffolding

• Challenge: Ask students to predict and measure the mass of classroom items like a stapler or a glue stick using two different non-standard units, then compare the counts and explain any differences.
• Scaffolding: Provide a visual checklist with pictures of the balance scale steps for students who need structure during Station Rotation.
• Deeper exploration: Introduce the idea of 'unit size matters' by having students create their own non-standard unit (e.g., a 'pencil unit') and measure the same object with both their unit and counters to compare results.

Key Vocabulary

Mass	Mass is how much 'stuff' or matter is in an object. We measure it to see how heavy or light something is.
Balance Scale	A tool with two pans used to compare the mass of objects. It tells us if one side is heavier, lighter, or if both sides have the same mass.
Non-standard Unit	An object used for measuring that is not a recognized unit like grams or kilograms. Examples include counters, paper clips, or blocks.
Equal Mass	When two objects or groups of objects have the same amount of mass, making the balance scale level.