Science lesson plan · 8th grade (Year 9 in England) · 30 minutes
Current, voltage and resistance (V = IR)
Electricity and magnetism
CCSS NGSS.HS-PS3-1England: KS3 Physics: Electricity and electromagnetism (current electricity)England: KS4 Combined Science: Electricity
Objective and success criteria
Students will: Current, voltage and resistance (V = IR).
- 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: Circuit symbols, cells and voltage
Leads to: Series and parallel circuits; Electrical power, charge and energy; Charge, current and time (Q = I t)
Materials: Circuit kits (cells, wires, bulbs), Circuit symbol cards, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (Circuit symbols, cells and voltage). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- A circle with a cross inside it stands for… (a buzzer / a cell / a resistor / a lamp (bulb)) → a lamp (bulb)Prompt: It looks like a glowing filament.
- A gap in a line with a small hinged line (lifted up) stands for… (an open switch / a cell / a closed switch / a bulb) → an open switchPrompt: The gap means the circuit is broken.
- A circle with the letter M inside stands for… (a magnet / a mirror / a meter / a motor) → a motorPrompt: The letter is a clue.
Hook · 3 min
- Show a circuit with a gap and ask why the bulb doesn't light.
- Share the objective: Current, voltage and resistance (V = IR). 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 current of 2 A flows through a 12 Ω resistor. What is the potential difference (voltage) across it, in V?
- Step 1: V = 2 × 12 = 24
- Step 2: So the answer is: 24 V
- Answer: 24 V
- 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 current of 1 A flows through a 4 Ω resistor. What is the potential difference (voltage) across it, in V? → 4 VPrompt: V = I × R
- A 4 V supply is connected across a 8 Ω resistor. What current flows, in A? → 0.5 APrompt: Rearrange V = I R to find I.
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 12 V battery drives a current of 4 A through a lamp. What is the resistance of the lamp, in Ω? → 3 ΩPrompt: R = V ÷ I
- A current of 4 A flows through a 2 Ω resistor. What is the potential difference (voltage) across it, in V? → 8 VPrompt: V = I × R
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: Circuit symbols, cells and voltage.
- Use concrete materials: circuit kits (cells, wires, bulbs).
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Series and parallel circuits; Electrical power, charge and energy; Charge, current and time (Q = I t).
- 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-8.
Free lesson plan from eurekami.com/lesson-plan-builder