Energy Transfers, Stores, and Efficiency
This lesson introduces Year 9 students to the fundamentals of energy transfers, moving beyond simple types of energy to focusing on stores, pathways, and the conservation of energy. It includes mathematical applications through efficiency calculations and visual representation via Sankey diagrams.
Learning objectives
- Identify different energy stores and pathways in common scenarios.
- State and apply the Law of Conservation of Energy to explain energy transfers.
- Calculate the efficiency of an energy transfer using the standard formula.
- Interpret and construct Sankey diagrams to represent energy transfers.
Lesson plan (60 minutes)
Introduction · 5 min
Do Now: List as many types of energy as you can remember from Key Stage 3.
Direct Instruction · 10 min
Teacher-led explanation of energy stores, pathways, and the Law of Conservation.
Worked Example · 10 min
Class walk-through of a Sankey diagram and efficiency calculation.
Independent Practice · 20 min
Differentiated worksheet practice (Support, Core, Stretch).
Feedback · 5 min
Peer marking of worksheets using the provided answer key.
Plenary · 10 min
Multiple-choice exit quiz to check for understanding.
Key vocabulary
- Thermal Energy Store
- The internal energy of an object due to the motion of its particles.
- Chemical Energy Store
- Energy stored in the bonds of chemical compounds (food, fuel, batteries).
- Kinetic Energy Store
- Energy an object has because of its movement.
- Conservation of Energy
- Energy cannot be created or destroyed, only transferred.
- Dissipated Energy
- Energy that is transferred to a store that is not useful (usually thermal).
Core worksheet (first questions)
- Describe the energy transfer in a petrol car moving at a constant speed.
- State the Law of Conservation of Energy in your own words.
- A toaster uses 200J of energy. 150J is used to toast the bread. How much energy is wasted?
- Calculate the efficiency of the toaster in the previous question.
Quiz (sample)
1. What is the Law of Conservation of Energy?
- A. Energy can be created if enough force is applied.
- B. Energy is used up and disappears eventually.
- C. Energy cannot be created or destroyed, only transferred.
- D. Energy is only conserved in closed systems with no friction.
2. What is the standard unit of energy?
- A. Newtons (N)
- B. Watts (W)
- C. Joules (J)
- D. Amps (A)
3. What energy store is found in food and fuels?
- A. Kinetic
- B. Chemical
- C. Nuclear
- D. Gravitational Potential
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