Reducing and Increasing Friction

Active exploration helps students connect abstract ideas about friction to their own experiences with moving objects. When children test surfaces and materials themselves, they build lasting understanding of forces that act in daily life. These hands-on investigations make invisible forces visible and measurable.

• Year 2
• Science
• 4 activities
• 25 min–40 min

Learning Objectives

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

Problem-Based Learning

⏱ 35 min·Small Groups

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.

Prepare & details

Design an experiment to reduce friction on a sliding block.

Facilitation Tip: During Ramp Testing, remind students to keep the block’s starting point and push force the same for each surface to ensure fair comparisons.

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Problem-Based Learning

⏱ 30 min·Pairs

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.

Prepare & details

Analyze how oil helps reduce friction in a machine.

Facilitation Tip: For the Wheel Challenge, have students count wheels and note which arrangements slide fastest and which grip best to see the trade-off between speed and control.

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Problem-Based Learning

⏱ 25 min·Small Groups

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.

Prepare & details

Justify why car tires have treads to increase friction.

Facilitation Tip: In the Oil Experiment, provide small droppers so students apply the same amount of oil to each ramp section, preventing uneven coverage that skews results.

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Problem-Based Learning

⏱ 40 min·Pairs

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.

Prepare & details

Design an experiment to reduce friction on a sliding block.

Facilitation Tip: When building Tire Tread Models, use masking tape on cardboard to create clear patterns students can compare side by side on the ramp.

Setup: Groups at tables with access to research materials

Materials: Problem scenario document, KWL chart or inquiry framework, Resource library, Solution presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management
• Relationship Skills

Teaching This Topic

Teachers should emphasize that friction isn’t just present or absent, but varies by surface and condition. Avoid oversimplifying by showing students how even seemingly smooth surfaces create resistance. Research suggests children learn best when they test their own ideas, so frame activities as experiments where predictions can be wrong and that’s part of learning. Model how to record data in tables and use graphs to spot trends over time.

What to Expect

Successful learning looks like students using precise vocabulary, making predictions, collecting data, and explaining why friction changes with different surfaces or tools. They should connect their findings to real-world objects like bicycle brakes or skateboard wheels.

Watch Out for These Misconceptions

Common Misconception

During Ramp Testing: Surface Variations, watch for students assuming only rough surfaces create friction.

What to Teach Instead

Pause the activity and have students feel the surfaces with their fingertips, then predict which will slow the block most. After testing, revisit their predictions to show that even glass causes friction that can be measured.

Common Misconception

During Wheel Challenge: Add or Remove Wheels, watch for students believing wheels remove friction entirely.

What to Teach Instead

Ask students to compare the time it takes for the block with and without wheels. Use their data to explain that wheels change sliding friction to rolling friction, which is still present but smaller.

Common Misconception

During Oil Experiment: Lubricant Test, watch for students thinking oil makes surfaces completely slippery.

What to Teach Instead

Have students apply oil to a small section of the ramp and compare its speed to a dry section. Discuss why some friction remains, linking it to microscopic surface interactions.

Assessment Ideas

Exit Ticket

After Wheel Challenge: Add or Remove Wheels, give students a card with a picture of a bicycle. Ask them to write one sentence about where friction is reduced (wheels) and one sentence about where friction is increased (brakes) on the bicycle.

Quick Check

During Oil Experiment: Lubricant Test, 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

After Tire Tread Model: Grip Stations, 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, linking their tread models to real-world needs.

Extensions & Scaffolding

• Challenge: Students design a shoe sole with the best grip for wet surfaces, testing their tread models on a damp ramp.
• Scaffolding: Provide sentence starters for students to describe their predictions and results, such as 'I think the _____ surface will be fastest because...'
• Deeper exploration: Introduce the concept of air resistance by having students compare how a flat piece of cardboard and a folded paper airplane slide down the ramp.

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.