Science lesson plan · 9th grade (Year 10 in England) · 30 minutes
Work done, power and energy costs
Energy
CCSS NGSS.HS-PS3-1CCSS NGSS.HS-PS3-3England: KS3 Physics: Energy (calculation of fuel uses and costs)England: KS4 Combined Science: Energy
Objective and success criteria
Students will: Work done, power and energy costs.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Kinetic and gravitational potential energy
Leads to: the next skill in this area.
Materials: Wind-up toys or a pendulum, Energy transfer diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (Kinetic and gravitational potential energy). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- What is the kinetic energy of a 2 kg object moving at 2 m/s? Use Eₖ = ½ m v². → 4 JPrompt: Square the speed first.
- An object of mass 10 kg is lifted 20 m. How much gravitational potential energy does it gain? Use Eₚ = m g h with g = 9.8 N/kg. → 1960 JPrompt: Multiply mass, gravitational field strength and height.
- A ball is dropped from 80 m. Ignoring air resistance, all its gravitational potential energy becomes kinetic energy. How fast is it moving just before it lands, in m/s? Use g = 10 N/kg. → 40 m/sPrompt: Set m g h = ½ m v². The mass cancels.
Hook · 3 min
- Wind up a toy or stretch an elastic band and ask where the energy goes.
- Share the objective: Work done, power and energy costs. Read the success criteria together.
I do: model it · 7 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: A force of 20 N pushes a box 40 m along the floor. How much work is done, in J?
- Step 1: W = 20 × 40 = 800
- Step 2: So the answer is: 800 J
- Answer: 800 J
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 6 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- A force of 20 N pushes a box 12 m along the floor. How much work is done, in J? → 240 JPrompt: work done = force × distance moved in the direction of the force
- An appliance transfers 120000 J of energy in 60 s. What is its power, in watts? → 2000 WPrompt: power = energy transferred ÷ time
You do: independent practice · 7 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 6 questions are on the student sheet below, with answers in the key.
Exit ticket · 3 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- A 0.1 kW heater is used for 5 hours. Electricity costs 25 cents (pence) per kWh. How much does it cost to run, in cents (pence)? → 12.5Prompt: Energy in kWh = power in kW × time in hours.
- A force of 150 N pushes a box 12 m along the floor. How much work is done, in J? → 1800 JPrompt: work done = force × distance moved in the direction of the force
Watch out for
- Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
- Remembering facts without the reason: ask "why?" and "what is the evidence?"
Support and stretch
Support
- Review first: Kinetic and gravitational potential energy.
- Use concrete materials: wind-up toys or a pendulum.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.
Free lesson plan from eurekami.com/lesson-plan-builder