Things That Stay Still or Keep Moving

Active learning works for this topic because students need to feel the difference between rest and motion directly. Handling objects that resist change builds intuition beyond abstract definitions. The activities let students test their own ideas, which is essential when misconceptions about forces and motion feel intuitive but are wrong.

• 5th Year
• Principles of the Physical World: Senior Cycle Physics
• 4 activities
• 20 min–35 min

Learning Objectives

1. Explain the concept of inertia as it applies to objects at rest and in motion.
2. Analyze the role of external forces, such as friction and air resistance, in changing an object's state of motion.
3. Compare and contrast the effects of inertia on passengers in a vehicle during sudden acceleration and deceleration.
4. Identify situations where Newton's first law is demonstrated in everyday scenarios.

Experiential Learning

⏱ 25 min·Small Groups

Demonstration: Index Card Flick

Place a coin atop an index card stretched over a cup. Students flick the card sharply sideways; the coin drops into the cup due to inertia. Groups repeat with varying flick speeds and coin masses, recording outcomes and predicting results.

Prepare & details

Why does a ball stop rolling if you don't keep pushing it?

Facilitation Tip: For the Index Card Flick, remind students to flick the card sharply and directly downward so the coin’s inertia keeps it in place while the card moves.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

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

Experiential Learning

⏱ 35 min·Pairs

Low-Friction Cart Push

Set up smooth tracks or rulers as low-friction surfaces. Students push toy cars or carts with equal force, measure travel distances, and compare to rough surfaces. Discuss net forces like air resistance and friction.

Prepare & details

What makes a toy car stay in place until you push it?

Facilitation Tip: In the Low-Friction Cart Push, ask students to measure the distance traveled after each push and compare how a heavier load slows acceleration more than a lighter one.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

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

Experiential Learning

⏱ 30 min·Pairs

Seatbelt Simulation

Hold a raw egg or small ball against a partner's chest with a string 'seatbelt.' Jerk forward suddenly to simulate braking; without restraint, the object continues forward. Pairs switch roles and vary speeds.

Prepare & details

How does a seatbelt help you when a car stops suddenly?

Facilitation Tip: During the Seatbelt Simulation, have students time how long it takes for the dummy to come to rest with and without the ‘seatbelt’ (string) so they see the difference in stopping time.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

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

Experiential Learning

⏱ 20 min·Whole Class

Class Line March

Whole class forms a line holding shoulders. Leader stops abruptly; observe chain reaction of bodies continuing forward. Debrief on inertia in crowds or buses.

Prepare & details

Why does a ball stop rolling if you don't keep pushing it?

Facilitation Tip: For the Class Line March, use a stopwatch to record how long it takes each student to stop when you call ‘freeze,’ then discuss how their inertia affects the stopping distance.

Setup: Varies; may include outdoor space, lab, or community setting

Materials: Experience setup materials, Reflection journal with prompts, Observation worksheet, Connection-to-content framework

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

Teaching This Topic

Research shows that hands-on motion activities reduce the persistence of Aristotelian ideas about motion. Avoid over-explaining inertia before students experience it; let their observations drive the discussion. Use consistent language, such as ‘net force’ and ‘inertial mass,’ so students build accurate mental models from the start.

What to Expect

Students will confidently explain that objects stay still or move steadily unless a net force acts, and they will connect this to real-world examples like seatbelts. They should use correct language, such as inertia as a property, not a force. Observing peers’ trials will help them refine their models of motion.

Watch Out for These Misconceptions

Common Misconception

During the Low-Friction Cart Push, watch for students attributing the cart’s slowing to ‘running out of push’ rather than friction or air resistance.

What to Teach Instead

Ask students to push the cart on different surfaces and compare distances: a smooth floor versus a carpet. This lets them see how friction changes motion, reinforcing that slowing requires a force.

Common Misconception

During the Index Card Flick, watch for students explaining the coin’s movement as the card ‘pushing’ it forward.

What to Teach Instead

Have students repeat the flick while gently blowing on the coin after the card moves to show that air does not cause the coin to move; inertia keeps it in place.

Common Misconception

During the Class Line March, watch for students describing stopping as a result of ‘the force running out.’

What to Teach Instead

Ask students to explain why they keep moving forward after ‘freeze’ is called. Have them model the motion with their hands to show their own inertia in action.

Assessment Ideas

Exit Ticket

After the Low-Friction Cart Push, provide a scenario: a heavy box is pushed on a smooth floor versus a rough floor. Ask students to write one sentence explaining how inertia and friction affect the box’s motion in each case.

Discussion Prompt

During the Seatbelt Simulation, ask: ‘What would happen to the dummy if the string broke during the sudden stop?’ Facilitate a class discussion where students use the term inertia to explain their predictions and link it to real car safety.

Quick Check

After the Index Card Flick, show a short clip of a magician pulling a tablecloth from under dishes. Ask students to identify the object exhibiting inertia, describe its initial state, and explain what force is acting to change that motion.

Extensions & Scaffolding

• Challenge students to design a ramp for the cart that maximizes distance traveled after a single push, using different surfaces to test friction effects.
• Scaffolding: Provide a data table for the Low-Friction Cart Push with columns for mass, push force, and distance traveled to guide struggling students in organizing their measurements.
• Deeper exploration: Have students research how seatbelts distribute force during a crash and compare their simulation results to real safety data.

Key Vocabulary

Inertia	The tendency of an object to resist changes in its state of motion. An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction.
Net Force	The overall force acting on an object when all forces are combined. If the net force is zero, the object's motion does not change.
Friction	A force that opposes motion between two surfaces in contact. It is a common force that causes moving objects to slow down and eventually stop.
State of Motion	Describes whether an object is at rest or moving at a constant velocity (constant speed and direction).