Science · Year 5 · Forces in Action · Summer Term

Reducing and Increasing Friction

Exploring practical applications of friction, including ways to reduce it (lubrication) and increase it (treads).

• National Curriculum Attainment Targets
• NC-KS2-Science-Y5-Forces-2

About This Topic

Friction acts as a force that slows or stops motion between surfaces in contact. Year 5 students examine ways to reduce it through lubrication, such as oil on bicycle chains to make parts move smoothly, and to increase it with treads on trainers or car tyres for better grip. These investigations address key questions about explaining lubricants, comparing scenarios for high or low friction, and designing targeted solutions.

This topic anchors the Forces in Action unit by linking friction to push and pull forces in everyday engineering. Students analyse contexts like slippery playground slides needing more grip or fast skateboards requiring less drag. Through fair testing on ramps with varied surfaces, they collect data on speed and stopping distance, building skills in prediction, measurement, and evaluation.

Active learning excels here because students directly manipulate variables like wax, sand, or oil on inclines, observing immediate effects on toy cars or marbles. Group trials promote discussion of evidence, while design tasks encourage creativity and iteration, making force concepts concrete and relevant to their world.

Key Questions

1. Explain how lubricants reduce friction in machines.
2. Compare situations where we want to increase friction versus decrease it.
3. Design a solution to either increase or decrease friction for a specific problem.

Learning Objectives

• Explain how lubricants reduce friction between moving parts in simple machines.
• Compare the effectiveness of different materials (e.g., oil, wax, dry) in reducing friction on a ramp.
• Design and construct a simple device that increases friction for a specific purpose, such as improving grip.
• Analyze the trade-offs between increasing and decreasing friction in everyday scenarios.

Before You Start

Introduction to Forces

Why: Students need a basic understanding of forces as pushes or pulls before exploring friction as a specific type of force.

Properties of Materials

Why: Understanding that different materials have different properties, such as smoothness or roughness, is essential for investigating friction.

Key Vocabulary

Friction	A force that opposes motion when two surfaces rub against each other. It can slow things down.
Lubricant	A substance, like oil or grease, that is put between moving surfaces to make them slide more easily and reduce friction.
Tread	A pattern on the surface of tires or shoes designed to increase grip by providing more points of contact and channeling away water or debris.
Surface Area	The total area of the outside surfaces of an object. Different surface areas can affect how much friction occurs.

Watch Out for These Misconceptions

Common Misconception

Friction only occurs on rough surfaces.

What to Teach Instead

Smooth surfaces still produce friction, though less than rough ones; lubricants reduce it further by creating a slippery layer. Ramp experiments with polished wood versus oiled versions let students quantify differences, challenging assumptions through data.

Common Misconception

Lubricants completely remove friction.

What to Teach Instead

Lubricants lower friction but do not eliminate it, allowing controlled motion. Students discover this in timed ramp tests comparing dry, wet, and oiled paths, fostering peer debates on partial effects.

Common Misconception

We always want to reduce friction.

What to Teach Instead

High friction prevents slips in safety-critical situations like braking. Group discussions after tread tests on inclines highlight trade-offs, helping students balance contexts.

Active Learning Ideas

Stations Rotation: Friction Tweakers

Prepare four stations with ramps: test plain wood, oiled wood, sandpaper, and rubber treads. Students release identical toy cars from the top, time descents with stopwatches, and note which surface speeds up or slows motion most. Groups rotate, pooling data for class graphs.

45 min·Small Groups

Design Challenge: Grip Enhancers

Pairs identify a problem like wet floors, then prototype shoe soles using card, glue, and textures like string or sand. Test on soapy trays by timing walks or slides. Iterate based on results and peer feedback before presenting best designs.

35 min·Pairs

Ramp Investigation: Lubricant Effects

Whole class sets up identical ramps. Individuals predict, then apply cooking oil or soap to surfaces and race marbles, measuring distances slid. Record before-and-after times in tables, discussing why changes occur.

30 min·Individual

Surface Hunt: Real-World Friction

Small groups survey school areas for high and low friction spots, like grass versus tiles. Test with dragged objects, rate friction levels, and propose improvements such as adding gravel paths. Share findings in a class map.

40 min·Small Groups

Real-World Connections

• Mechanics use lubricants like motor oil and grease to reduce wear and tear on car engines and bicycle chains, ensuring smooth operation and longevity.
• Shoe designers create different tread patterns for athletic footwear, like football boots or running shoes, to maximize grip on various surfaces and prevent slips.
• Engineers designing ski lifts or roller coasters carefully consider friction. They use lubricants on moving parts to reduce resistance but design braking systems that intentionally increase friction to stop safely.

Assessment Ideas

Exit Ticket

Provide students with two scenarios: 1) a bicycle chain needing to move smoothly, and 2) a steep slide needing more grip. Ask them to write one sentence for each scenario explaining whether friction should be increased or decreased and name one method to achieve this.

Discussion Prompt

Pose the question: 'Imagine you are designing a new type of skateboard wheel. What would be the advantages and disadvantages of making the wheels very smooth versus very rough?' Facilitate a class discussion comparing the impact of friction in this context.

Quick Check

Show students images of different objects (e.g., ice skates, car tires, sandpaper, a greased pan). Ask them to hold up a green card if the object is designed to reduce friction and a red card if it is designed to increase friction. Follow up by asking them to justify their choice for one or two examples.

Frequently Asked Questions

How do lubricants reduce friction in machines?

Lubricants form a thin film between surfaces, allowing them to slide past each other with less resistance. In Year 5 lessons, students see this on oiled axles or chains, timing rotations to measure smoother motion. This links to real machines like clocks or bikes, emphasising maintenance for efficiency.

What are practical examples of increasing friction?

Treads on shoes grip wet pavements, tyre patterns channel water for road traction, and sand on icy paths adds roughness. Students explore these through testing textured materials on ramps, comparing stopping distances to everyday safety applications.

How can active learning help teach friction control?

Hands-on ramp races with lubricants and grips give direct evidence of friction's effects, far beyond diagrams. Collaborative stations build data skills as groups compare results, while design challenges spark problem-solving. These methods make abstract forces tangible, boosting retention and enthusiasm.

How to design activities for friction misconceptions?

Use prediction sheets before ramp tests to surface ideas like 'smooth means no friction,' then reveal data showing otherwise. Peer teaching in pairs during redesigns corrects views collaboratively. Track progress with before-after quizzes tied to fair test evidence.