Mathematics · Primary 1

Active learning ideas

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.

• MOE Syllabus Outcomes
• MOE: M(ii).3
• MOE: M(ii).4

• 20–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• 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.

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.

What to look for

Provide students with a balance scale, a set of counters, and two different small objects (e.g., an eraser and a toy car). Ask: 'Which object do you think is heavier? Use the counters and the scale to find out. How many counters does each object need to balance?'

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

Activity 02

• 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.

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.

What to look for

Give each student a card with a drawing of a balance scale. One pan has a picture of 5 blocks, and the other pan has a picture of 3 blocks. Ask: 'Which side is heavier? Draw more blocks on the lighter side to make the scale balance. Write the total number of blocks on each side when it is balanced.'

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

Activity 03

• 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.

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.

What to look for

Present students with two different non-standard units, such as large buttons and small beads. Ask: 'If we use buttons to measure the mass of a book, and then use beads to measure the mass of the same book, will we get the same number? Why or why not? What is important about the units we use?'

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

Activity 04

• 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.

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

What to look for

Provide students with a balance scale, a set of counters, and two different small objects (e.g., an eraser and a toy car). Ask: 'Which object do you think is heavier? Use the counters and the scale to find out. How many counters does each object need to balance?'

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

A few notes on teaching this unit

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.

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

• 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.

  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.

• 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.

  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.

• 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.

  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.

---

Methods used in this brief

• Stations Rotation
• Experiential Learning