Science lesson plan · 8th grade (Year 9 in England) · 45 minutes
Series and parallel circuits
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: Series and parallel circuits.
- 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: Current, voltage and resistance (V = IR)
Leads to: Current and voltage rules in series and parallel circuits
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 · 5 min
- Quick retrieval from earlier learning (Current, voltage and resistance (V = IR)). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- A current of 2 A flows through a 2 Ω resistor. What is the potential difference (voltage) across it, in V? → 4 VPrompt: V = I × R
- A 20 V supply is connected across a 20 Ω resistor. What current flows, in A? → 1 APrompt: Rearrange V = I R to find I.
- A 0.75 V battery drives a current of 0.25 A through a lamp. What is the resistance of the lamp, in Ω? → 3 ΩPrompt: R = V ÷ I
Hook · 5 min
- Show a circuit with a gap and ask why the bulb doesn't light.
- Share the objective: Series and parallel circuits. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Two resistors of 8 Ω and 14 Ω are connected in series. What is their total resistance, in Ω?
- Step 1: 8 + 14 = 22
- Step 2: So the answer is: 22 Ω
- Answer: 22 Ω
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 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 parallel circuit has two branches. The current in one branch is 0.3 A and in the other is 0.4 A. What is the current from the battery, in A? → 0.7 APrompt: In parallel, the branch currents add up to the total current.
- Why are lights in a house wired in parallel? (If one breaks, they all go off / So the current is the same everywhere / Each can be switched on and off separately and gets the full voltage / It uses less wire) → Each can be switched on and off separately and gets the full voltagePrompt: What happens in series if one bulb breaks?
You do: independent practice · 10 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 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Why are lights in a house wired in parallel? (Each can be switched on and off separately and gets the full voltage / So the current is the same everywhere / It uses less wire / If one breaks, they all go off) → Each can be switched on and off separately and gets the full voltagePrompt: What happens in series if one bulb breaks?
- Two resistors of 8 Ω and 15 Ω are connected in series. What is their total resistance, in Ω? → 23 ΩPrompt: In series, resistances add.
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: Current, voltage and resistance (V = IR).
- 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: Current and voltage rules in series and parallel circuits.
- 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