Science · Year 3

Active learning ideas

Measuring Forces

Children learn to connect abstract numbers to real pushes and pulls through hands-on measurement. When students see a spring scale stretch as they lift a book or slide a block, the link between force and motion becomes visible. This tactile experience builds the concrete foundation needed before students analyze forces in diagrams or equations.

• ACARA Content Descriptions
• AC9S4U03
• AC9S3I03

• 15–30 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Stations Rotation
• 15 min · Whole Class

Whole Class Demo: Spring Scale Introduction

Hook a spring scale to common objects like books or bags. Lift slowly while reading the scale, noting newtons for each. Discuss how extension matches force. Students copy readings into notebooks.

Explain how a spring scale measures force.

Facilitation Tip

During the Whole Class Demo, invite students to predict how far the spring will stretch before touching the object, then compare predictions to actual readings.

What to look for

Provide students with a spring scale and two objects of different masses. Ask them to record the force (in Newtons) needed to lift each object. Then, ask: 'Which object required a larger force to lift, and why?'

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

Activity 02

• Stations Rotation
• 30 min · Small Groups

Small Groups: Friction Surface Test

Place objects on surfaces like carpet, tile, and sandpaper. Groups pull with spring scale at constant speed, record forces. Swap surfaces and compare data on charts.

Compare the force needed to lift different objects.

Facilitation Tip

Before the Small Groups Friction Surface Test, assign each group one surface so they can collect comparable data and discuss differences at the end.

What to look for

On an index card, have students draw a spring scale and label the parts that show the force. Ask them to write one sentence explaining how the scale works to measure force.

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

Activity 03

• Stations Rotation
• 25 min · Pairs

Pairs: Lifting Challenge Experiment

Pairs select objects of similar size but different masses. Measure lift force with scale, swap roles. Predict and test if predictions hold, discuss surprises.

Design an experiment to measure the force of friction on various surfaces.

Facilitation Tip

For the Pairs Lifting Challenge, provide objects with masses clearly labeled in grams so students focus on force readings rather than guessing weights.

What to look for

Pose the question: 'Imagine you are pushing a box across different surfaces: carpet, wood, and ice. Which surface do you think will require the most force to push the box? Explain your reasoning using the term friction.'

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

Activity 04

• Stations Rotation
• 20 min · Individual

Individual: Force Diary Extension

Students measure forces at home, like pulling a door or pushing a chair. Record with sketches and newtons next lesson. Share one entry in class circle.

Explain how a spring scale measures force.

What to look for

Provide students with a spring scale and two objects of different masses. Ask them to record the force (in Newtons) needed to lift each object. Then, ask: 'Which object required a larger force to lift, and why?'

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

A few notes on teaching this unit

Start with a live demonstration so students see the spring extend under load and understand the cause-and-effect relationship. Use guided questions to help them connect the scale’s markings to the force applied, avoiding premature explanations of Hooke’s law. Repeated, structured practice with the same objects builds reliable measurement habits before open-ended investigations.

Students will use spring scales to read forces in newtons, compare results across different surfaces, and explain how friction and mass affect the force needed to move objects. Clear labeling of results and thoughtful predictions show growing confidence in using measurement tools.

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Watch Out for These Misconceptions

• During the Pairs Lifting Challenge Experiment, watch for students who assume the heavier object always needs more force without testing.

  Ask students to record both mass and force in a simple table, then circle the object that required more force. Prompt them to notice when two objects of different masses require the same force because one is easier to lift due to shape or friction.

• During the Whole Class Demo: Spring Scale Introduction, watch for students who call the scale a ‘weight measurer’ rather than a ‘force measurer’.

  After showing the scale stretch under a pull, ask students to read the number while lifting the scale itself. Ask, ‘Is the scale measuring the object’s weight or the pull we give it?’ Use the term force consistently when recording readings.

• During the Small Groups Friction Surface Test, watch for students who believe more force always causes faster movement.

  Give each pair a stopwatch and ask them to pull objects at a steady pace over each surface. Point out that the scale reading shows how much force is needed, not how fast the object moves, and discuss why a higher reading might slow movement due to friction.

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Methods used in this brief

• Stations Rotation