Science · Year 2 · Forces in Motion · Term 2

Reducing and Increasing Friction

Students will explore ways to reduce friction (e.g., wheels, oil) and increase friction (e.g., rough surfaces).

• ACARA Content Descriptions
• AC9S2U03

About This Topic

Friction acts as a force that slows or stops motion between two surfaces in contact. In Year 2, students investigate methods to reduce friction, such as adding wheels to a sliding block or applying oil to surfaces, and ways to increase it, like using rough textures or treads on tires. These explorations align with AC9S2U03, where students examine how friction affects everyday objects and design simple tests to change its effects.

This topic connects physical science to real-world applications, from playground slides to bicycle chains. Students analyze why car tires need grooves for grip on wet roads and how lubricants keep machines running smoothly. Such investigations foster skills in fair testing, prediction, and evidence-based explanations, preparing students for more complex force studies in later years.

Active learning shines here because friction is directly observable and testable. When students modify ramps with different surfaces or race wheeled versus sliding toys, they see cause-and-effect relationships firsthand. Group experiments encourage collaboration and discussion, turning abstract forces into concrete experiences that stick.

Key Questions

1. Design an experiment to reduce friction on a sliding block.
2. Analyze how oil helps reduce friction in a machine.
3. Justify why car tires have treads to increase friction.

Learning Objectives

• Design a simple experiment to compare the effect of different surfaces on the sliding distance of an object.
• Explain how adding wheels reduces friction between a surface and an object.
• Analyze how oil or grease acts as a lubricant to decrease friction in moving parts.
• Justify why rough surfaces or treads increase friction for better grip.

Before You Start

Push and Pull Forces

Why: Students need to understand basic forces like pushing and pulling to grasp how friction opposes motion.

Properties of Materials

Why: Understanding that materials can be rough or smooth is foundational to exploring how surfaces affect friction.

Key Vocabulary

Friction	A force that opposes motion when two surfaces rub against each other. It can slow things down.
Surface	The outside part or layer of an object. Different surfaces can feel rough or smooth.
Lubricant	A substance, like oil or grease, that is put on surfaces to make them slide more easily and reduce friction.
Treads	Patterns on the surface of tires or shoes that help them grip surfaces, increasing friction.

Watch Out for These Misconceptions

Common Misconception

Friction only happens on rough surfaces.

What to Teach Instead

Surfaces that look smooth still produce friction due to microscopic bumps. Hands-on ramp tests with glass, wood, and polished metal help students measure and compare friction levels, revealing it exists everywhere motion occurs.

Common Misconception

Reducing friction always makes things better.

What to Teach Instead

Less friction aids speed in some cases, like skates, but more is needed for control, such as brakes. Station activities let students test both, discussing trade-offs in real scenarios like sports or vehicles.

Common Misconception

Wheels eliminate friction completely.

What to Teach Instead

Wheels change sliding friction to rolling friction, which is smaller but present. Wheel races versus sliders demonstrate this quantitatively, with students graphing data to see the reduction, not removal.

Active Learning Ideas

Ramp Testing: Surface Variations

Build ramps from cardboard and test a block sliding down smooth wood, sandpaper, and fabric. Students predict speed, time descents with a stopwatch, and record which surface increases or reduces friction. Discuss results as a class.

35 min·Small Groups

Wheel Challenge: Add or Remove Wheels

Provide blocks and toy wheels. Pairs attach wheels to one block and leave another plain, then race them down inclines. Measure distances traveled and note how wheels reduce friction. Repeat with added weight.

30 min·Pairs

Oil Experiment: Lubricant Test

Set up trays with dry and oiled surfaces. Students slide small cars across both, timing motion and observing differences. Wipe and retest to confirm oil's role in reducing friction. Chart findings.

25 min·Small Groups

Tire Tread Model: Grip Stations

Create model tires from clay with smooth, grooved, and rough patterns. Roll them on wet paper towels and dry surfaces, rating grip levels. Students justify why treads increase friction for safety.

40 min·Pairs

Real-World Connections

• Mechanics in car repair shops use lubricants like oil and grease to reduce friction in engines and other moving parts, making vehicles run more smoothly and last longer.
• Playground designers choose materials for slides and surfaces. Smooth, polished surfaces reduce friction for faster sliding, while rougher surfaces on climbing structures increase friction for better grip.
• Shoe manufacturers design treads on the soles of athletic shoes to increase friction, providing athletes with better traction and preventing slips during sports like running or basketball.

Assessment Ideas

Exit Ticket

Give students a card with a picture of a bicycle. Ask them to write one sentence about where friction is reduced and one sentence about where friction is increased on the bicycle.

Quick Check

Present students with three objects: a toy car, a ramp covered in sandpaper, and a small bottle of oil. Ask students to predict which object will help a block slide fastest down the ramp and explain why, using the terms friction, lubricant, or surface.

Discussion Prompt

Pose the question: 'Why do we need friction sometimes, but want to reduce it other times?' Facilitate a class discussion, guiding students to provide examples for both reducing and increasing friction in everyday situations.

Frequently Asked Questions

How do I teach reducing friction to Year 2 students?

Start with familiar examples like slippery slides or oiled hinges. Guide students to design ramp experiments testing wheels, balls, or soap, timing motion to quantify changes. This builds prediction skills and links to AC9S2U03 through fair tests.

Why do car tires have treads?

Treads increase friction by channeling water away and gripping roads, preventing slips. Students model this with clay tires on wet surfaces, observing how grooves improve traction. Class debates reinforce why increasing friction enhances safety.

What experiments show oil reduces friction?

Use toy cars on trays: slide on dry surfaces, then add oil or soap solution and compare distances or times. Students record videos or drawings of motion differences. This direct comparison clarifies lubrication's role in machines.

How can active learning help teach friction?

Active approaches like group ramp challenges or wheel-building tasks make friction visible and measurable. Students predict, test variables such as surfaces or loads, and share data, which deepens understanding over lectures. Collaborative analysis corrects misconceptions through peer evidence, aligning with inquiry-based science in the Australian Curriculum.