Changes in Speed: Getting Faster and Slower

Active learning builds conceptual bridges between abstract force ideas and observable motion. This topic asks students to trace unbalanced forces through real, measurable changes in speed. Hands-on trials make the invisible forces of friction and gravity tangible, so students can test predictions and refine explanations through direct evidence.

• 5th Year
• Principles of the Physical World: Senior Cycle Physics
• 4 activities
• 30 min–45 min

Learning Objectives

1. Identify everyday objects that are speeding up or slowing down.
2. Describe the qualitative change in speed for an object rolling down an incline.
3. Explain how unbalanced forces cause changes in an object's speed.
4. Compare the effect of different surfaces on the rate at which a toy car slows down.

Experiential Learning

⏱ 45 min·Small Groups

Ramp Challenges: Speed Variations

Build ramps from books at three angles. Release identical balls or cars from the top, observe and time speed changes. Switch to rough surfaces for slowing effects, then discuss forces involved.

Prepare & details

Describe what happens to the speed of a ball rolling down a hill.

Facilitation Tip: During Ramp Challenges, circulate with a timer and ask each group to predict where they expect the ball to be fastest, then compare predictions to their stopwatch measurements.

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

Toy Car Tracks: Acceleration Stations

Set stations with straight tracks, inclines, and curves. Students push cars gently, note speeding up or slowing, and record descriptions. Groups compare results and vote on best examples.

Prepare & details

Give examples of things that get faster and things that get slower.

Facilitation Tip: For Toy Car Tracks, assign each station a different surface material and have students rotate in teams, timing runs and ranking surfaces by deceleration.

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·Small Groups

Outdoor Motion Hunt: Real-World Observations

Students walk school grounds noting speeding up (e.g., downhill runs) and slowing (e.g., against wind). Sketch paths, describe changes, and share photos in class debrief.

Prepare & details

How can you make a toy car go faster or slower?

Facilitation Tip: On the Outdoor Motion Hunt, give students clipboards with a simple chart so they can sketch and label real-world examples of speed changes they observe.

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

⏱ 40 min·Whole Class

Video Slow-Motion Analysis: Braking Bikes

Show bike braking videos in slow motion. Pause to predict speed changes, then measure frame-by-frame. Students draw force diagrams based on visuals.

Prepare & details

Describe what happens to the speed of a ball rolling down a hill.

Facilitation Tip: When using Video Slow-Motion Analysis, pause the clip at key frames and ask students to sketch velocity arrows above the bike to show changes in speed.

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

Start with concrete motion examples students already know, like braking in a car or rolling a ball. Avoid abstract force diagrams early; instead, let students feel and measure real forces first. Research shows that pairing prediction with measurement builds stronger mental models than demonstrations alone. Use peer discussion to surface misconceptions before formal instruction, so students revise ideas through evidence rather than teacher explanation.

What to Expect

Students will confidently use terms like acceleration, deceleration, friction, and unbalanced forces to explain why objects speed up, slow down, or keep moving. They will design simple experiments, record data, and justify their conclusions with clear evidence from their trials.

Watch Out for These Misconceptions

Common Misconception

During Ramp Challenges, watch for students assuming the ball slows down on its own after leaving their hands.

What to Teach Instead

Set up a prediction table on the board labeled 'What will happen when the ball is released?' and ask groups to write their reasoning. After trials, revisit the table to replace 'it slows down' with 'friction and air resistance act against the ball's motion' based on their measurements.

Common Misconception

During Toy Car Tracks, watch for students believing a continuous push is needed for speeding up.

What to Teach Instead

Ask each team to start their car with a gentle push and then release it. Have them note where the car speeds up (on the ramp) and where it slows down (on carpet), then explain the role of gravity and friction using their data.

Common Misconception

During Outdoor Motion Hunt, watch for students attributing all slowing to air resistance.

What to Teach Instead

Bring students back to a classroom surface station and have them test how different materials (carpet, tile, sandpaper) affect a toy car’s motion. Discuss why friction dominates on surfaces compared to air resistance in still air conditions.

Common Misconception

Common Misconception

Common Misconception

Common Misconception

Common Misconception

Common Misconception

Common Misconception

Common Misconception

Common Misconception

Common Misconception

Assessment Ideas

Exit Ticket

Provide students with three scenarios: a car starting from a stoplight, a ball rolling to a stop, and a bicycle moving at a constant speed. Ask them to write 'speeding up', 'slowing down', or 'constant speed' for each scenario and briefly explain why.

Quick Check

Ask students to stand up and demonstrate 'speeding up' with their hands and 'slowing down' with their hands. Then, call out an object (e.g., 'a dropped apple', 'a skateboarder braking') and have them show the correct motion.

Discussion Prompt

Pose the question: 'Imagine you are pushing a shopping cart. What would make it speed up? What would make it slow down? What would make it stop completely?' Facilitate a class discussion, guiding students to use terms like force, friction, and pushing.

Extensions & Scaffolding

• Challenge students to predict and test how changing the ramp angle affects acceleration, then extend to a mini-lab comparing mass and acceleration using marbles of different sizes.
• Scaffolding: Provide pre-labeled force arrows on ramp diagrams for students to match to their observations during Ramp Challenges.
• Deeper exploration: Have students research how engineers design braking systems in cars and bicycles, then present their findings with annotated diagrams linking friction and safety.

Key Vocabulary

Speed	The rate at which an object covers distance. It tells us how fast something is moving.
Acceleration	The rate at which an object's speed increases. This happens when an object speeds up.
Deceleration	The rate at which an object's speed decreases. This happens when an object slows down.
Force	A push or a pull that can cause an object to change its motion, including its speed.