Inertia and Momentum

Overview

This is lesson 3 of 16 in Unlocking Biophysical Principles in PE. Students build on prior learning about forces and movement by exploring how inertia and momentum influence sporting performance through demonstrations, practical observation and applied examples.

Learning intentions

• WALT understand inertia and momentum in physical movements.
• WALT identify how force, mass and velocity affect momentum.
• WALT apply biomechanical principles to sporting situations.
• WALT communicate observations using appropriate PE terminology.

Success criteria

• I can define inertia and momentum in my own words.
• I can give accurate examples of inertia and momentum in sport.
• I can explain how changing force, mass or velocity affects movement.
• I can work safely and contribute useful observations during a group demonstration.

Curriculum links

• Understanding in context: explain how biophysical principles influence movement in physical activity.
• Developing practical knowledge: explore and apply movement concepts through safe participation.
• Communicating and interpreting: use evidence from movement to describe and explain performance.
• Key competencies: thinking; managing self; participating and contributing; relating to others.

Lesson structure (60 minutes)

1. 0–5 min · Hook and prior knowledge. Teacher opens with the hook and learning intentions and asks, “Why does a moving rugby player not stop instantly when they reach the line?” Students discuss with a partner, then share one idea connecting the question to force or motion.

2. 5–15 min · Direct teaching. Teacher uses the inertia and momentum explanation slides to clarify that inertia is an object’s tendency to remain at rest or continue moving unless an external force acts on it. Explain that momentum describes the quantity of motion and is calculated as mass × velocity; greater mass or speed produces greater momentum. Students complete the key-term section of the biomechanics observation worksheet and use sporting examples such as a sprinter leaving the blocks, a football being stopped, or a cyclist braking.

3. 15–25 min · Teacher demonstrations. Teacher demonstrates inertia using a stationary ball and a moving ball, and momentum using balls of different masses or the same ball at different speeds. Emphasise safe spacing, controlled force and stopping before collecting equipment. Students predict what will happen, observe the result and record the movement, external force and outcome on the biomechanics observation worksheet.

4. 25–42 min · Small-group practical investigation. Teacher places students in five groups of four and displays the practical investigation instructions. Each group rotates through three short activities: a stationary object being moved by an external force; a moving object being stopped or redirected; and a controlled sport movement such as a sprint start, jump landing or pass. Students take turns as performer, observer, safety checker and recorder. They identify where inertia and momentum are present and explain how speed, mass or applied force changes the movement.

5. 42–51 min · Apply to sport. Teacher displays the sport scenario prompts and assigns each group one situation: a basketball player stopping suddenly, a goalkeeper saving a fast shot, a rugby player changing direction, a long jumper landing, or a tennis player returning serve. Students use their observations and the biomechanics observation worksheet to prepare a 30-second explanation identifying inertia, momentum and the external force involved.

6. 51–57 min · Share and peer check. Teacher invites each group to present its explanation and prompts the class to challenge or extend the reasoning: “What would happen if the athlete moved faster?” or “How could the athlete reduce or redirect momentum?” Students listen for correct use of terminology and add one improvement or connection to their worksheet.

7. 57–60 min · Plenary and exit response. Teacher returns to the hook through the review and exit prompt. Students independently write: “Inertia is…”, “Momentum is…”, and one sporting example explaining the external force that changes the movement. Collect worksheets to identify students needing further support in the next lesson.

Resources

• the complete inertia and momentum lesson deck
• the biomechanics observation worksheet
• Soft balls of different sizes or masses
• Cones to mark safe working areas
• Stopwatches or timing apps
• Open gym, turf or court space
• Whiteboard and markers
• First-aid kit and suitable footwear

Assessment

• Check predictions and questioning during the demonstrations for accurate understanding of inertia, momentum and external force.
• Use group observation records and explanations to assess whether students can apply the concepts to movement rather than simply define them.
• Collect the final written response as an exit check, looking for an accurate definition and a relevant sporting example.

Differentiation

• Provide a word bank and sentence starters on the worksheet, such as “The object continues moving because…” and “Momentum increases when…”.
• Pair students strategically and assign clear group roles; allow students who are less confident physically to contribute as observer, recorder or safety checker.
• Use larger, slower and highly visible demonstrations before progressing to sport-specific movements. Offer verbal instructions, teacher modelling and repeated demonstrations for students with processing, language or attention needs.
• Support EAL learners with diagrams, gestures and familiar sporting contexts. Check understanding privately and accept labelled drawings or an oral explanation where extended writing is a barrier.
• Challenge advanced learners to compare two examples, explain the effect of changing mass and velocity, or propose how an athlete could safely absorb, stop or redirect momentum.