Physics — Electricity · Lesson 4a

Electron Flow in Metals

⚡🔋💡🧲🔌

Spec 2.16 · Navigation: Arrow Keys or Spacebar

🎯 Learning Objectives:

✔ 2.16 – Know that electric current in solid metallic conductors is a flow of negatively charged electrons.
✔ Next lesson (L4b): series circuit calculations (2.19).

🏆 Success Criteria — I will…

state that current in a metal is a flow of negatively charged electrons
describe the difference between electron flow (− to +) and conventional current (+ to −)
explain why metals conduct but insulators don't, using free electrons

🖨️ Pupil Packs

✂️ Arrival cut-cards:

Page 1 of every pack = title, LOs & success criteria for that tier.

⏱️ 40-Minute Pacing Guide

Core path (~30 min planned, ~39 in room): Arrival → Starter → I Do (Electron Flow) → Observe (sim) → We Do (Label the Wire) → Independent → Exit Ticket

One teaching cycle this lesson — electron flow only. Series calculations are the next lesson (L4b).

⏱️ 4 min

Arrival Task

Arrival Task – Recall from Lesson 2

Instructions: Answer from memory. Q1–3 recall V = I × R from Lesson 2. Q4 leads into today.

1. 🟢

Which formula links voltage (V), current (I) and resistance (R)?

A) V = I + RB) V = I × RC) V = I − R

B) V = I × R

2. 🟢

Current is the rate of flow of…?

A) heatB) chargeC) light

B) charge

3. 🟢

A 3 A current flows through a 4 Ω resistor. What is the voltage?

💡 V = I × R, so 3 × 4

A) 7 VB) 1.3 VC) 12 V

C) 12 V (V = 3 × 4 = 12)

4. Lead-in ⚡

What tiny particles carry the charge inside a metal wire — and what charge do they have?

A) protons (+)B) electrons (−)C) neutrons (0)

B) electrons, which are negatively charged

1. 🟠

A 12 V battery pushes current through a 6 Ω resistor. What is the current?

💡 I = V ÷ R, so 12 ÷ 6

A) 2 AB) 72 AC) 0.5 A

A) 2 A (I = 12 ÷ 6 = 2)

2. 🟠

Which sentence best defines current?

A) the rate of flow of charge (coulombs per second)B) the amount of resistance in a wireC) the voltage of the battery

A) the rate of flow of charge — 1 A = 1 coulomb per second

3. 🟠

A lamp has 9 V across it and 0.5 A flowing through it. What is its resistance?

💡 R = V ÷ I, so 9 ÷ 0.5

A) 4.5 ΩB) 18 ΩC) 9.5 Ω

B) 18 Ω (R = 9 ÷ 0.5 = 18)

4. Lead-in ⚡

We draw current flowing + to −, but electrons really flow the other way. Why do scientists still use the old direction?

A) electrons really do flow + to −B) they agreed + to − before electrons were discovered, and kept it as the standardC) it makes the maths easier

B) conventional current (+ to −) was agreed before electrons were discovered, so it became the global standard

1. 🔵

A hairdryer draws 10 A on UK mains (230 V). Calculate its resistance. Show working.

R = V ÷ I = 230 ÷ 10 = 23 Ω

2. 🔵

Explain why increasing the voltage across a fixed resistor increases the current, using ideas about charge.

Higher voltage gives more energy per coulomb, pushing electrons faster through the circuit. Since current is the rate of flow of charge, faster electron flow = higher current. R stays constant, so by V = IR, if V↑ then I↑.

3. 🔵

Two resistors of 10 Ω and 20 Ω are in series with a 6 V battery. Calculate the current.

R_total = 10 + 20 = 30 Ω. I = V ÷ R = 6 ÷ 30 = 0.2 A

4. Lead-in ⚡

In the circuit above, the voltage across the 10 Ω resistor is 2 V and across the 20 Ω it's 4 V. What do you notice when you add these together? Why?

2 + 4 = 6 V, which equals the battery voltage. In series, the voltages across each component add up to the total supply voltage.

⏱️ 3 min

Starter

Starter: True or False?

Instructions: ✍️ Write it — copy each statement into your book and write TRUE or FALSE, then correct the false ones. 🎮 Tap it — vote on the board as a class. 3 minutes.

📝 True or False?

1. Electrons flow from the negative terminal to the positive terminal. ________

2. Electrons are positively charged. ________

3. In a series circuit, the current is the same at every point. ________

4. Adding a second resistor in series decreases the total resistance. ________

5. In series, every component gets the full battery voltage. ________

6. Metals conduct because their electrons are free to move. ________

💡 Hint

Q1: which way do the negative electrons get pushed? Away from the − terminal…

Qs 3–5 are the series rules — same current everywhere, voltages share. Watch out: three of these are false!

💡 Answers to discuss: 1. TRUE. 2. FALSE — negatively charged. 3. TRUE. 4. FALSE — it increases total resistance. 5. FALSE — that's parallel; in series the voltages share and add up to the supply. 6. TRUE.

💡 Did You Know?

An electron in a wire actually moves incredibly slowly — about 0.1 mm per second (slower than a snail!). But the electrical signal travels at nearly the speed of light because each electron pushes the next one, like dominoes.

⏱️ 3 min

I Do

I Do: Electron Flow in Metals (2.16)

Key Idea: Electric current in solid metallic conductors is a flow of negatively charged electrons.

⚡ What Actually Moves?

Inside a metal wire, there are billions of free electrons — they are not locked to any single atom.

When a battery provides voltage, it pushes these free electrons through the wire — this is current.

Electrons are negatively charged, so they flow from the negative terminal to the positive terminal.

🔄 Two Directions!

Conventional current: + → − (what we draw on diagrams)

Electron flow: − → + (what actually happens)

Scientists agreed on conventional current before discovering electrons, and it stuck.

🌍 Why This Matters

When engineers design fairy lights, phone chargers, or car dashboards, they need to know exactly how voltage is shared between components in series. Get the calculation wrong and the component burns out — or doesn't work at all. This is real engineering maths.

💡 Why do metals conduct? Metal atoms are arranged in a lattice. The outer electrons are delocalised (free to move). Non-metals like plastic don't have free electrons, so they are insulators.

Inside a Metal Wire

If the question says "describe the current in a metal wire" — say: "a flow of negatively charged electrons". This is the exact spec wording worth 1 mark.

⚠️ Misconception alert: "The lamp uses up the electrons."
Truth: Electrons are never used up — the same electrons keep looping round the circuit. It's energy that gets transferred to the lamp.

🔑 Keywords to Know

Electron	A tiny negatively-charged particle. Carries current in metals.
Charge	A property of particles. Measured in coulombs (C).
Conventional current	The "pretend" flow from + to − (opposite to electrons).
Series	Components on a single loop. Current same, voltages add.

⏱️ 3 min

Observe 👀

Observe: Electrons on the Move

Watch for ONE thing: when the circuit is switched on, which way do the moving electrons (the little dots) travel — towards + or towards −? Tap to load the simulation, then we'll say the answer together.

⚡ Circuit simulation — see the electrons flow

Build: battery → wire → bulb. Then tick Show Current → Electrons to watch them flow.

🔗 Open PhET sim (new tab) 🔗 Electron-drift animation (backup)

✍️ Say it / write it — sentence stems

"The moving dots in the wire are the ______________."

"They flow from the __________ terminal to the __________ terminal."

"So electron flow goes ____ to ____ (the opposite of the arrows we draw)."

The sim shows the real electron direction (− → +). The arrows you usually draw — conventional current — point the other way (+ → −).

🌟 Finished early? Add a second bulb to the circuit. Do the electrons speed up, slow down, or keep flowing the same way? Have a go at saying why.

⏱️ 5 min

We Do

We Do: Label the Wire 🏷️

Instructions: Select a label from the bank, then click the correct slot. Match all 8!

👥 Think-Pair-Share: Try it yourself → discuss with your partner → agree on the answer.

Electrons Negative Metal ions Fixed − to + + to − Amps (A) Insulators

Part A: Inside the Wire

The charge carriers in metals are ?

Their charge is ?

The large particles that don't move are ?

These ions are ? in position

Part B: Directions & Units

Electron flow direction: ?

Conventional current direction: ?

Current is measured in ?

Plastics and rubber are ?

Matched: 0 / 8

⏱️ 8 min

Independent Work

Instructions: Complete the tasks in your printed pack independently.

📝 Your Pack Contains:

Section A: Multiple Choice — 4 questions

Section B: Short Answer — calculations + definitions

Section C: Long Answer — explain + calculate

Section D: Exam-Style Question — full marks breakdown

Need help? Check the Scaffolding Sheet for the series rules and step-by-step method.

📝 Exam Command Words:
State = write a fact, no explanation needed.
Calculate = show the formula, substitute, get the answer + unit.
Explain = say what happens AND why (use "because").
Describe = say what happens step by step (no "why" needed).

🏆 Success Criteria

Foundation (Grades U–1): I can state that electrons carry current in metals and that they are negatively charged.

Middle (Grades 1–2): I can describe electron flow vs conventional current and explain why metals conduct.

Higher (Grades 3–5): I can describe current using exact spec wording and explain conduction in terms of delocalised electrons.

✅ Tick as you go — Success checklist

I can state that electrons carry current in metals

I know electron flow is − to +

I can explain why metals conduct (free electrons)

I can name an insulator and say why it cannot conduct

⏱️ 3 min

Exit Ticket

Exit Ticket – Cumulative Recap (L1 · L2 · Today)

Instructions: 6 questions — 2 from each lesson. Answer from memory. No notes.

🟢 I'm confident — I could teach this

🟡 Getting there — need more practice

🔴 I'm stuck — I need help

1. Draw the circuit symbol for a lamp.

Circle with a cross inside.

2. State one difference between series and parallel.

Series: one loop / parallel: branches. (Or any valid difference.)

3. Write the formula linking V, I and R.

V = I × R

4. A 2 A current flows through a 5 Ω resistor. Find V.

V = 2 × 5 = 10 V

Today

5. What particles carry current in a metal wire?

Electrons (negatively charged).

Today

6. What charge does an electron have, and which way do electrons flow round a circuit?

Negative charge. Electrons flow from − to +.

⚡ Next lesson (L4b): Series circuit calculations — R_total, current, and how voltage is shared between resistors.

Electron Flow in Metals

Physics · Electricity · Lesson 4a | Spec 2.16

🟢 Foundation Pack (Grades U–1)🟠 Middle Pack (Grades 1–2)🔵 Higher Pack (Grades 3–5)

Name: ________________________________ Date: ________________ Class: __________

🎯 Learning Objective

2.16 — Know that electric current in solid metallic conductors is a flow of negatively charged electrons.

🏆 Success Criteria — I will…

☐ state that electrons carry the current in metals

☐ state that electrons are negatively charged

☐ say which way electrons flow (− to +)

☐ explain the difference between electron flow (− to +) and conventional current (+ to −)

☐ explain why metals conduct but plastics do not

☐ correct the misconception that electrons are "used up"

☐ describe current using the exact spec wording: a flow of negatively charged electrons

☐ explain conduction in terms of delocalised electrons

☐ explain why the electrical signal is fast even though electrons drift slowly

🗺️ Today's route

Arrival Task → Starter → I Do (Electron Flow) → We Do (Label the Wire) → Independent Work → Exit Ticket

Before we start — how confident do you feel about electricity? (circle one) 🔴 Stuck 🟡 Getting there 🟢 Confident

📋 Exam Technique — Every Mark Counts!

State / Name = a short fact, no explanation.

Describe = say what happens, step by step.

Explain = say what happens AND why (use "because").

Golden rule: Write something for every question.

Knowledge Organiser: Electron Flow in Metals (L4a)

How to use: Read this before starting. Refer back during independent work. Cover it up for the exit ticket — that tests what you actually remember!

Concept	Details
Current in metals	A flow of negatively charged electrons through a metallic conductor. (Learn this exact sentence — it is worth a mark.)
Free electrons	Outer electrons in metals are delocalised — free to move through the lattice of fixed positive metal ions.
Conventional current	Drawn from + to − on diagrams (historical convention, agreed before electrons were discovered).
Electron flow	Real direction: − to + (opposite to conventional current).
Why metals conduct	Their free electrons can move and carry charge when a voltage pushes them.
Insulators	Materials like plastic with no free electrons. Charge cannot flow.
Charge	A property of particles, measured in coulombs (C). Current = rate of flow of charge.
Common mistake	Electrons are not used up — they keep looping. It is energy that is transferred to the lamp.

🧠 Memory Tricks

Electrons are Negative → flow − to +.

Conventional current = the "pretend" arrow (+ to −).

Conductor vs insulator = free electrons or not.

Arrival Task – Foundation (U–1) 🟢

✂️ Cut along the dashed lines and give one card to each pupil. Tick your answer.

Which formula links V, I and R?

A) V = I + RB) V = I × RC) V = I − R

Current is the rate of flow of…?

A) heatB) chargeC) light

3 A flows through a 4 Ω resistor. Voltage? (💡 V = I × R)

A) 7 VB) 1.3 VC) 12 V

Which particles carry charge in a metal wire — and what charge?

A) protons (+)B) electrons (−)C) neutrons (0)

Arrival Task – Middle (1–2) 🟠

✂️ Cut along the dashed lines and give one card to each pupil. Tick your answer.

12 V battery, 6 Ω resistor. Current? (💡 I = V ÷ R)

A) 2 AB) 72 AC) 0.5 A

Which sentence best defines current?

A) rate of flow of charge (C/s)B) amount of resistanceC) the battery's voltage

Lamp: 9 V across it, 0.5 A through it. Resistance? (💡 R = V ÷ I)

A) 4.5 ΩB) 18 ΩC) 9.5 Ω

Why do scientists still draw current + to − when electrons flow the other way?

A) electrons do flow + to −B) agreed before electrons were foundC) it changes the maths

Arrival Task – Higher (3–5) 🔵

✂️ Cut along the dashed lines and give one card to each pupil. Show your working on the card.

Hairdryer: 10 A on 230 V mains. Calculate R. Show working.

Explain why increasing V across a fixed R increases I (use charge ideas).

10 Ω + 20 Ω in series, 6 V battery. Calculate the current.

V across 10 Ω = 2 V, across 20 Ω = 4 V. What do you notice? Why?

Starter: True or False?

Write TRUE or FALSE. Correct any false statements.

#	Statement	T / F	Correction (if false)
1	Electrons flow from the negative terminal to the positive terminal.
2	Electrons are positively charged.
3	In a series circuit, the current is the same at every point.
4	Adding a second resistor in series decreases the total resistance.
5	In series, every component gets the full battery voltage.
6	Metals conduct because their electrons are free to move.

We Do Worksheet – Label the Wire

Fill in each blank with the correct word from the bank.

1. The charge carriers in metals are _______________

2. Their charge is _______________

3. The large particles that don't move are _______________

4. Electron flow direction: _______________

5. Conventional current direction: _______________

6. Current is measured in _______________

7. A material with no free electrons (cannot conduct) is an _______________

Word bank: Electrons · Negative · Metal ions · − to + · + to − · Amps (A) · Insulator

Scaffolding Sheet – Electron Flow

The Key Facts

Current in a metal = a flow of negatively charged electrons.

Electron flow: − → + Conventional current: + → −

Metals conduct because their outer electrons are free / delocalised.

Plastics are insulators — no free electrons, so no charge can flow.

Sentence Starters (for explain questions)

"Current in a metal is a flow of…"

"Metals conduct because their electrons are…"

"Electrons are not used up because…"

Watch Out!

❌ "Protons carry the current" → ✅ electrons (negative).

❌ "Electrons get used up" → ✅ energy is transferred; electrons keep looping.

Independent Work – Foundation (Grades U–1)

You've got this! Use your scaffolding sheet. Tick or write your answer for each question.

Section A: Multiple Choice

1. Electric current in a metal wire is a flow of…

[ ] Protons [ ] Neutrons [ ] Electrons

2. Electrons have a _______ charge.

[ ] Positive [ ] Negative [ ] No charge

3. Metals conduct electricity because their electrons are…

[ ] Stuck to atoms [ ] Free to move [ ] Positive

4. Electrons flow from…

[ ] + to − [ ] − to + [ ] They don't move

Section B: Short Answer

5. State what carries the electric current inside a metal wire.

6. State the charge on an electron. 💡 one word

7. Name one material that cannot conduct electricity (an insulator).

Section C: Scaffolded (Grade 2 Challenge)

8. (4 marks) A student wrote: "Current in a wire is a flow of positive protons."

Hint: each part is one short answer.

(a) What actually carries the current? [1]

(b) What charge does that particle have? [1]

(d) Name one material that cannot conduct, and say why. [1]

Section D: Describe

9. (3 marks) Describe what happens to the electrons inside a metal wire when the battery is switched on. 💡 free electrons → pushed by voltage → flow − to +

Independent Work – Middle (Grades 1–2)

Push yourself! Full sentences for explain questions — use the word "because".

Section A: Recall

1. Conventional current flows from…

[ ] − to + [ ] + to − [ ] Either direction

2. The fixed particles left behind in a metal are called…

[ ] Electrons [ ] Metal ions [ ] Protons

3. State the difference between electron flow and conventional current.

Section B: Explain

4. Explain why metals can conduct electricity but plastics cannot. 💡 mention free / delocalised electrons

5. A pupil says "the lamp uses up the electrons." Explain what is actually used up, and what happens to the electrons.

Section C: Long Answer

6. (4 marks) (a) Describe, in terms of particles, what electric current is in a metal wire. [2]

(b) Explain why increasing the voltage pushes more current through the wire. 💡 energy per coulomb [2]

Section D: Stretch (Grade 3)

7. (3 marks) Using the word delocalised, explain why metals are good conductors and how charge travels through the whole length of the wire.

Independent Work – Higher (Grades 3–5)

Aim high! Reason in full sentences. Show the examiner you understand the physics, not just the words.

Section A: Spec Recall

1. Describe electric current in a metal using the exact spec wording. [2 marks]

2. Explain why conventional current direction is still used today, even though it is the "wrong" way. [2 marks]

Section B: Explain

3. Explain why metals conduct electricity but a covalent solid such as plastic does not. Refer to electron structure. [3 marks]

Section C: Apply Your Understanding

4. The electrical signal travels along a wire almost instantly, yet individual electrons drift very slowly (about 0.1 mm/s). Explain how both statements can be true. [3 marks]

Section D: Evaluate (Grade 5 Challenge)

5. (3 marks) Evaluate the statement: "Current is used up as it travels round a circuit." Explain what is conserved and what is transferred.

Exit Ticket – Foundation (U–1) — Cumulative Recap

Name: _________________________ Date: _____________

1) Draw the circuit symbol for a lamp.

2) State one difference between series and parallel.

3) Write the formula linking V, I and R.

4) I = 2 A, R = 5 Ω. Calculate V.

Today

5) What particles carry current in metals?

Today

6) What charge does an electron have, and which way do they flow?

Exit Ticket – Middle (1–2) — Cumulative Recap

1) How must an ammeter and voltmeter be connected?

2) Give two golden rules for circuit diagrams.

3) Define current in terms of charge.

4) V = 9 V, R = 3 Ω. Calculate I.

Today

5) Electron flow vs conventional current direction?

Today

6) Why do metals conduct but plastics do not?

Exit Ticket – Higher (3–5) — Cumulative Recap

1) Explain why an ammeter in parallel is dangerous.

2) Why are houses wired in parallel? Two reasons.

3) Explain why increasing V across a fixed R increases I.

4) 230 V hairdryer, 5 A. Calculate R.

Today

5) Metals vs plastics: why do metals conduct?

Today

6) Electron flow vs conventional current — the difference, and why both are used?

Electron Flow in Metals

🖨️ Pupil Packs

⏱️ 40-Minute Pacing Guide

Arrival Task – Recall from Lesson 2

1. 🟢

2. 🟢

3. 🟢

4. Lead-in ⚡

1. 🟠

2. 🟠

3. 🟠

4. Lead-in ⚡

1. 🔵

2. 🔵

3. 🔵

4. Lead-in ⚡

Starter: True or False?

📝 True or False?

💡 Hint

💡 Did You Know?

I Do: Electron Flow in Metals (2.16)

⚡ What Actually Moves?

🔄 Two Directions!

🌍 Why This Matters

Inside a Metal Wire

🔑 Keywords to Know

Observe: Electrons on the Move

✍️ Say it / write it — sentence stems

We Do: Label the Wire 🏷️

Part A: Inside the Wire

Part B: Directions & Units

Independent Work

📝 Your Pack Contains:

🏆 Success Criteria

✅ Tick as you go — Success checklist

Exit Ticket – Cumulative Recap (L1 · L2 · Today)

🧑‍🏫 TA Focus —

🎲 Cold Call

📋 Teacher Notes — L4

At a glance

⏱️ Route & timings

⚠️ Misconceptions to ambush

🎯 Differentiation

📸 Evidence

⚡ Next lesson

Lesson Complete!

Electron Flow in Metals

🎯 Learning Objective

🏆 Success Criteria — I will…

🗺️ Today's route

📋 Exam Technique — Every Mark Counts!

Knowledge Organiser: Electron Flow in Metals (L4a)

🧠 Memory Tricks

Arrival Task – Foundation (U–1) 🟢

Arrival Task – Middle (1–2) 🟠

Arrival Task – Higher (3–5) 🔵

Starter: True or False?

We Do Worksheet – Label the Wire

Fill in each blank with the correct word from the bank.

Scaffolding Sheet – Electron Flow

The Key Facts

Sentence Starters (for explain questions)

Watch Out!

Independent Work – Foundation (Grades U–1)

Section A: Multiple Choice

Section B: Short Answer

Section C: Scaffolded (Grade 2 Challenge)

Section D: Describe

Independent Work – Middle (Grades 1–2)

Section A: Recall

Section B: Explain

Section C: Long Answer

Section D: Stretch (Grade 3)

Independent Work – Higher (Grades 3–5)

Section A: Spec Recall

Section B: Explain

Section C: Apply Your Understanding

Section D: Evaluate (Grade 5 Challenge)

Exit Ticket – Foundation (U–1) — Cumulative Recap

Exit Ticket – Middle (1–2) — Cumulative Recap