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Primary Science · Year 4Chapter 10 · Switches, conductors and insulators
Year 4 · Chapter 10

Switches, conductors and insulators

By the end of this chapter you will be able to

  • Explain that a switch opens and closes a circuit, and link this to whether the lamp lights
  • Use a conductor tester to decide whether a material is a conductor or an insulator
  • Name some conductors, and say that metals are good conductors
  • Name some insulators, and say why wires have an insulating coating
  • Explain how a switch uses both a conductor and an insulator
  • Plan a fair test to check whether a material is a conductor

You should already know

  • The parts of a series circuit, and when a lamp lights (Year 4 Science, Chapter 9)
  • Materials and their properties, such as hard, soft and shiny (Year 4 Science, Chapter 6, and Year 1 Science)

Where this leads

  • Electricity and circuits in more detail, including voltage and components (Year 6 Science)
  • Building safe circuits with a grown-up, and choosing materials for a purpose (Year 5 and Year 6 Science)

National Curriculum for England, Key Stage 2 science, Year 4. Content: E4 recognise that a switch opens and closes a circuit, and associate this with whether or not a lamp lights in a simple series circuit, E5 recognise some common conductors and insulators, and associate metals with being good conductors.

Exercise P  Do you remember?

1
FWhen a lamp lights in a circuit, what must the loop be? Write the word: complete or broken.
2
FName one part of a series circuit that pushes the electricity round. Write the name.
3
FName one metal. Write one metal.
4
FWhich part of a circuit makes a sound when electricity flows through it? Write the word.
5
FIs plastic a solid or a liquid? Write the word.
10.1

A switch opens and closes a circuit

Year 4
E4: recognise that a switch opens and closes a circuit, and associate this with whether or not a lamp lights
Video lesson: A switch opens and closes a circuitComing soon
Story. Mo has a torch with a switch on the side. He slides it along, and the light comes on. He slides it back, and the light goes out. “What is the switch doing inside?” he asks. Ms Chen says, “It opens and closes the loop of the circuit.”

A switch is a part of a circuit that can be closed or open. When the switch is closed, it completes the loop, so the electricity can flow and the lamp lights. When the switch is open, the loop is broken, so the electricity cannot flow and the lamp does not light.

switch closed+-lamp lights
A closed switch: the loop is complete, so the lamp lights.
switch open+-lamp does not light
An open switch: the loop is broken, so the lamp does not light.

The table shows what happens in each position.

SwitchThe loopThe lamp
closedcompletelights
openbrokendoes not light

Key ideas

  • A closed switch completes the loop, so the lamp lights.
  • An open switch breaks the loop, so the lamp does not light.
  • A switch opens and closes the circuit.
  • Switching the lamp on and off means opening and closing the switch.
Worked example 10.1.1
Look at the table in section 10.1. Which switch position lights the lamp? Write the word: closed or open.

Method. Read the table.

  1. Find the lights row. The row that says lights is the closed switch.
    closed
  2. Name the position. So the switch must be closed for the lamp to light.
    closed
  3. Write the answer.
    closed

Check. A closed switch completes the loop. ✓

Worked example 10.1.2
When the switch is open, is the loop complete or broken? Write the word.

Method. Think about an open switch.

  1. Think about the loop. An open switch breaks the loop.
    breaks
  2. Name the state. So the loop is broken.
    broken
  3. Write the answer.
    broken

Check. The lamp does not light when the loop is broken. ✓

Worked example 10.1.3
Does a lamp light when the switch is open? Write yes or no.

Method. Read the table.

  1. Find the open row. The open row says the lamp does not light.
    does not light
  2. Decide. So the answer is no.
    no
  3. Write the answer.
    no

Check. An open switch breaks the loop. ✓

Watch out

Watch out: a switch is not a lamp. The switch controls whether the loop is complete. If the switch is closed but the bulb is broken, the lamp still does not light.

Try it at home or school (with a grown-up). With a grown-up, use a cell, a bulb in a holder, two wires and a simple switch to make a loop. Close the switch, and watch the bulb. Then open it. Do not touch the bulb while it is hot.

Exam tip

Grown-up tip. Ask: “Is the switch open or closed? Is the loop complete?” Let your child open and close the switch, and say what the lamp does each time.

Exercise 10A  A switch opens and closes a circuit

1
FDoes a closed switch complete the loop? Write yes or no.
2
FDoes an open switch break the loop? Write yes or no.
3
FDoes a lamp light when the switch is open? Write yes or no.
4
FFill in the gap: a switch opens and ___ a circuit. Write the word.
5
FLook at the table in section 10.1. Which switch position lights the lamp? Write the word: closed or open.
6
FLook at the table in section 10.1. Which switch position leaves the loop broken? Write the word: closed or open.
7
FHow many positions does a simple on-off switch have? Write the number.
8
FWhich word describes the loop when the switch is open: complete or broken? Write the word.
9
PSRuby says a lamp lights when the switch is open. Is Ruby right? Write yes or no.
10
PSAli closes the switch. Does the electricity flow round the loop? Write yes or no.
11
PSWorking scientifically. Predict whether the lamp will light when the switch is closed. Write yes or no, and then test it with a grown-up.
12
RExplain how a switch turns a lamp on and off. Write one sentence.
10.2

Conductors and insulators: the tester

Year 4
E5: recognise some common conductors and insulators
Video lesson: Conductors and insulators: the testerComing soon
Story. Yusuf wants to know which materials let electricity flow through them. “We can use a loop with a lamp,” says Ms Chen. “If the lamp lights when we put the material in the gap, the material is a conductor.”

A conductor is a material that lets electricity flow through it. An insulator is a material that does not let electricity flow through it.

We can test a material with a conductor tester. It is a loop with a cell, a bulb and two clips. The material goes between the two clips. If it is a conductor, the material completes the loop and the lamp lights. If it is an insulator, the lamp stays off.

material+-lamp lights: conductor
The conductor tester with a conductor between the clips. The lamp lights.
material+-lamp stays off: insulator
The conductor tester with an insulator between the clips. The lamp stays off.

Key ideas

  • A conductor lets electricity flow through it, so the lamp lights in the tester.
  • An insulator does not let electricity flow, so the lamp stays off.
  • The conductor tester uses a cell, a bulb holder and two clips.
  • Only cells and a bulb holder are used in school tests, with a grown-up.
Worked example 10.2.1
In the tester, the lamp lights. Is the material a conductor or an insulator? Write the word.

Method. Read what the lamp shows.

  1. Read the result. A lamp that lights means the loop is complete.
    complete
  2. Name the material. So the material is a conductor.
    conductor
  3. Write the answer.
    conductor

Check. The material completed the loop. ✓

Worked example 10.2.2
In the tester, the lamp stays off. Is the material a conductor or an insulator? Write the word.

Method. Read what the lamp shows.

  1. Read the result. A lamp that stays off means the loop is not complete.
    not complete
  2. Name the material. So the material is an insulator.
    insulator
  3. Write the answer.
    insulator

Check. The insulator does not let the electricity through. ✓

Worked example 10.2.3
Which part of the tester is the lamp: bulb or switch? Write the word.

Method. Look at the picture of the tester.

  1. Look at the lamp. The lamp in the tester is the bulb, drawn as a circle with a cross inside.
    bulb
  2. Name the part. So the lamp is the bulb.
    bulb
  3. Write the answer.
    bulb

Check. The bulb is the lamp that lights. ✓

Watch out

Watch out: the tester checks whether a material lets electricity flow through it. A material that is hard, shiny or heavy is not automatically a conductor.

Try it at home or school (with a grown-up). With a grown-up, make a tester with a cell, a bulb holder and two wires with clips. Test a coin and a plastic ruler, one at a time, between the clips. Say which one lights the lamp.

Exam tip

Grown-up tip. Ask: “Does the lamp light? Is the material a conductor or an insulator?” Let your child predict the result before each test.

Exercise 10B  Conductors and insulators: the tester

1
FWhat is the name for a material that lets electricity flow through it? Write the word: conductor or insulator.
2
FWhat is the name for a material that does not let electricity flow through it? Write the word: conductor or insulator.
3
FIn the tester, a lamp lights. Is the material a conductor or an insulator? Write the word.
4
FIn the tester, a lamp stays off. Is the material a conductor or an insulator? Write the word.
5
FFill in the gap: a conductor completes the loop, so the lamp ___. Write the word.
6
FWhich part of the tester is the lamp? Write the word: bulb or switch.
7
FDoes a conductor let electricity flow through it? Write yes or no.
8
FDoes an insulator let electricity flow through it? Write yes or no.
9
FHow many clips does the conductor tester have? Write the number.
10
PSSam says a material that lights the lamp is an insulator. Is Sam right? Write yes or no.
11
PSWorking scientifically. Plan a fair test to check whether a material is a conductor. Write one thing that must stay the same each time.
12
RExplain why the tester uses a loop and a lamp. Write one sentence.
10.3

Metals are good conductors

Year 4
E5: recognise some common conductors, and associate metals with being good conductors
Video lesson: Metals are good conductorsComing soon
Story. Priya tests a copper coin, a steel paper clip, a plastic ruler and some aluminium foil in the tester. “The metal things light the lamp,” she says. Mr Patel says, “Metals are good conductors. Let us check with the full table.”

Metals are good conductors of electricity. Copper, steel, aluminium, iron and gold are all metals, and they are used for wires and for the parts of a circuit that carry the electricity.

Not every conductor is a metal. Pencil lead is made of graphite, which is not a metal, but it still lets electricity flow through it.

The table shows the results of the conductor tester for eight materials.

Material between the clipsKind of materialLamp lights? (conductor or insulator)
copper coinmetallights: conductor
steel paper clipmetallights: conductor
aluminium foilmetallights: conductor
pencil lead (graphite)not a metallights: conductor
plastic rulernot a metalstays off: insulator
rubber bandnot a metalstays off: insulator
wooden sticknot a metalstays off: insulator
glassnot a metalstays off: insulator

Key ideas

  • Metals are good conductors of electricity.
  • Copper, steel and aluminium are metals that conduct.
  • Pencil lead is a conductor, but it is not a metal.
  • Test each material with the same cell, bulb and clips.
Worked example 10.3.1
Look at the table in section 10.3. Is the copper coin a conductor or an insulator? Write the word.

Method. Find the copper coin row.

  1. Read the row. The copper coin is a metal, and the lamp lights for it.
    lights
  2. Name the kind. So the copper coin is a conductor.
    conductor
  3. Write the answer.
    conductor

Check. Copper is a good conductor. ✓

Worked example 10.3.2
How many metals are in the table? Write the number.

Method. Count the metal rows.

  1. Read the middle column. The metal rows are copper coin, steel paper clip and aluminium foil.
    three metals
  2. Count them. There are three metals in the table.
    3
  3. Write the answer.
    3

Check. The other five materials are not metals. ✓

Worked example 10.3.3
Are all the metals in the table conductors? Write yes or no.

Method. Check each metal row.

  1. Check the metals. The copper coin, steel paper clip and aluminium foil all light the lamp.
    all light
  2. Decide. So every metal in the table is a conductor, and the answer is yes.
    yes
  3. Write the answer.
    yes

Check. Metals are good conductors. ✓

Watch out

Watch out: a metal is not always the same as a good conductor in every case, but in this table every metal is a conductor. Do not assume that shiny things are metals.

Try it at home or school (with a grown-up). Test a copper coin, a steel paper clip and a plastic spoon with a grown-up, in a conductor tester with a cell and a bulb holder. Note which ones light the lamp. Do not test anything with mains electricity.

Exam tip

Grown-up tip. Ask: “Which material is a metal? Did the lamp light for every metal?” Let your child make a table of the materials and the results.

Exercise 10C  Metals are good conductors

1
FLook at the table in section 10.3. Which material is a conductor: copper coin or plastic ruler? Write the name.
2
FIs the steel paper clip a conductor? Write yes or no.
3
FIs aluminium foil a metal? Write yes or no.
4
FHow many metals are in the table in section 10.3? Write the number.
5
FAre all the metals in the table conductors? Write yes or no.
6
FHow many conductors are in the table in section 10.3? Write the number.
7
FIs pencil lead a metal? Write yes or no.
8
FIs pencil lead a conductor? Write yes or no.
9
FName a metal that is a conductor. Write one metal.
10
PSAli says all shiny things are conductors. Is Ali right? Write yes or no.
11
PSWorking scientifically. Predict whether a gold ring will be a conductor. Write yes or no, with a reason.
12
RExplain why metals are used for the parts of a circuit that carry electricity. Write one sentence.
10.4

Insulators in everyday life

Year 4
E5: recognise some common conductors and insulators
Video lesson: Insulators in everyday lifeComing soon
Story. Aisha looks at the wires in an old lamp. “The wire inside is metal, and the outside is coloured plastic,” she says. Mr Patel says, “The plastic is an insulator. It stops the electricity from leaving the wire.”

Insulators do not let electricity flow through them. Plastic, rubber, wood, glass and dry paper are common insulators.

Electrical wires have a plastic or rubber coating. The metal inside carries the electricity, and the insulating coating keeps the electricity inside the wire, so it does not reach our hands.

The table shows the results of the conductor tester for the four insulators, and the glass and the other materials.

Material between the clipsKind of materialLamp lights? (conductor or insulator)
copper coinmetallights: conductor
steel paper clipmetallights: conductor
aluminium foilmetallights: conductor
pencil lead (graphite)not a metallights: conductor
plastic rulernot a metalstays off: insulator
rubber bandnot a metalstays off: insulator
wooden sticknot a metalstays off: insulator
glassnot a metalstays off: insulator

Key ideas

  • An insulator does not let electricity flow through it.
  • Plastic, rubber, wood and glass are insulators.
  • Wires have an insulating coating to keep the electricity inside the wire.
  • The metal inside a wire is a conductor.
Worked example 10.4.1
Look at the table in section 10.4. Is the plastic ruler a conductor or an insulator? Write the word.

Method. Find the plastic ruler row.

  1. Read the row. The plastic ruler does not light the lamp.
    does not light
  2. Name the kind. So the plastic ruler is an insulator.
    insulator
  3. Write the answer.
    insulator

Check. Plastic is an insulator. ✓

Worked example 10.4.2
How many insulators are in the table? Write the number.

Method. Count the insulator rows.

  1. Read the table. The insulators are plastic ruler, rubber band, wooden stick and glass.
    four
  2. Count them. There are four insulators in the table.
    4
  3. Write the answer.
    4

Check. Four insulators and four conductors make eight materials. ✓

Worked example 10.4.3
Why is the coating on a wire made of plastic or rubber? Write the word: insulator.

Method. Think about the coating.

  1. Think about the coating. The coating stops the electricity from leaving the wire.
    stops
  2. Name the kind of material. Materials that stop electricity from flowing are insulators.
    insulator
  3. Write the answer.
    insulator

Check. A plastic or rubber coating is an insulator. ✓

Watch out

Watch out: glass is an insulator, so a glass cup does not carry electricity. But a glass object does not protect you from mains electricity, so never test it with mains.

Try it at home or school (with a grown-up). Look at the cable of a lamp at home with a grown-up. Find the plastic coating and the metal inside, if you can see them. Do not cut or touch any cable that is plugged in.

Exam tip

Grown-up tip. Ask: “What is the outside of the wire made of? Why does it need that covering?” Let your child explain that the coating is an insulator.

Exercise 10D  Insulators in everyday life

1
FLook at the table in section 10.4. Is the plastic ruler a conductor or an insulator? Write the word.
2
FIs a rubber band a conductor? Write yes or no.
3
FIs a wooden stick a conductor or an insulator in the table? Write the word.
4
FHow many insulators are in the table in section 10.4? Write the number.
5
FIs glass a conductor? Write yes or no.
6
FFill in the gap: electrical wires have a ___ coating that is an insulator. Write the word.
7
FName one everyday insulator from the table in section 10.4. Write one name.
8
FDoes an insulator complete a loop so that the lamp lights? Write yes or no.
9
PSHow many materials in the table are not metals? Write the number.
10
PSRuby says a wooden stick is a conductor, because it comes from a plant. Is Ruby right? Write yes or no.
11
PSWorking scientifically. Plan a safe test to check whether a dry sponge is a conductor. Write one thing you would do to keep the test fair.
12
RExplain why an insulating coating is put round a metal wire. Write one sentence.
10.5

Switches use both conductors and insulators

Year 4
E4 and E5: a switch uses a conductor to complete the loop and an insulator to keep the user safe
Video lesson: Switches use both conductors and insulatorsComing soon
Story. Leo looks inside a simple switch. “There is a metal part that touches to close the loop,” he says. “And the handle I press is plastic.” Ms Chen says, “Good. The metal conducts, and the plastic insulates. A switch needs both.”

A switch has metal contacts inside. When the switch is closed, the metal contacts touch, and they are conductors that complete the loop. The handle that you press is usually made of an insulator, such as plastic, so that the person using it is kept safe.

Choosing a material means thinking about what the material must do. A conductor is chosen where the electricity must flow, and an insulator is chosen where it must not.

Key ideas

  • The metal contacts of a switch are conductors.
  • The plastic handle of a switch is an insulator.
  • A conductor is chosen where the electricity must flow.
  • An insulator is chosen where the electricity must not flow.
Worked example 10.5.1
In a switch, which part completes the loop: the metal contacts or the plastic handle? Write the words.

Method. Think about the loop.

  1. Think about the contacts. When the metal contacts touch, the loop is complete.
    touch
  2. Name the part. So the metal contacts complete the loop.
    metal contacts
  3. Write the answer.
    the metal contacts

Check. The metal contacts are conductors. ✓

Worked example 10.5.2
Is the plastic handle of a switch a conductor or an insulator? Write the word.

Method. Think about the material.

  1. Think about plastic. Plastic does not let electricity flow through it.
    does not let
  2. Name the kind. So the plastic handle is an insulator.
    insulator
  3. Write the answer.
    insulator

Check. Plastic is an insulator, which keeps the user safe. ✓

Worked example 10.5.3
Should the handle of a switch be made of metal? Write yes or no.

Method. Think about safety.

  1. Think about the handle. A metal handle could carry electricity to the hand.
    carry electricity
  2. Decide. So the handle should not be metal, and the answer is no.
    no
  3. Write the answer.
    no

Check. The handle is an insulator, so the user is kept safe. ✓

Watch out

Watch out: a conductor is not always the best choice. In a circuit, the wires need a conductor, but the covering of the wires must be an insulator.

Try it at home or school (with a grown-up). Look at a switch on a torch or a toy, with a grown-up. Find the part you press, and say whether it is an insulator. Do not open any mains switch or socket.

Exam tip

Grown-up tip. Ask: “Which part do you press? Which part lets the electricity through?” Let your child name the conductor and the insulator in the switch.

Exercise 10E  Switches use both conductors and insulators

1
FIn a switch, which part completes the loop when it is closed? Write the words: metal contacts or plastic handle.
2
FIs the plastic handle of a switch a conductor or an insulator? Write the word.
3
FShould the handle of a switch be made of metal? Write yes or no.
4
FFill in the gap: a conductor is chosen where the electricity ___ flow. Write the word: must or must not.
5
FFill in the gap: an insulator is chosen where the electricity ___ flow. Write the words: must or must not.
6
FWhich material is better for a wire: copper or plastic? Write the word.
7
FWhich material is better for the covering of a wire: copper or plastic? Write the word.
8
FFill in the gap: a good conductor for a wire is a ___. Write the word.
9
PSSam says a plastic handle keeps the hand safe from electricity in a switch. Is Sam right? Write yes or no.
10
PSA wire has a metal core and a plastic cover. Which part carries the electricity? Write the words.
11
PSWorking scientifically. Predict which material will make the lamp light: a steel paper clip or a plastic ruler. Write the name.
12
RExplain why a switch needs both a conductor and an insulator. Write one sentence.

Chapter summary

SkillMethod
SwitchesA closed switch completes the loop, so the lamp lights. An open switch breaks the loop, so the lamp does not light.
ConductorsA conductor lets electricity flow through it, and it completes the loop in the tester. Metals are good conductors.
InsulatorsAn insulator does not let electricity flow. Plastic, rubber, wood and glass are insulators.
The conductor testerA cell, a bulb holder and two clips. The lamp lights for a conductor, and stays off for an insulator.
Switches and materialsMetal contacts are conductors. A plastic handle is an insulator that keeps the user safe.

Can you…?

  • I can say that a switch opens and closes a circuit, and whether the lamp lights
  • I can use a conductor tester to decide whether a material is a conductor or an insulator
  • I can say that metals are good conductors, and name some metals
  • I can name some insulators, and say why wires have an insulating coating
  • I can explain why a switch uses both a conductor and an insulator
  • I can plan a fair test to check whether a material is a conductor

Key terms

switch
a part that opens or closes a circuit
closed
a switch position that completes the loop, so the electricity can flow
open
a switch position that breaks the loop, so the electricity cannot flow
conductor
a material that lets electricity flow through it
insulator
a material that does not let electricity flow through it
metal
a material such as copper, steel or aluminium; metals are good conductors
graphite
a form of carbon that is used in pencil lead, and conducts electricity
coating
a covering round a wire, made of an insulator such as plastic
conductor tester
a loop with a cell, a bulb holder and two clips, used to test materials

Exercise 10Z  Check-up

1
Look at the table in section 10.1. Which switch position lights the lamp? Write the word: closed or open.
2
When an open switch breaks the loop, does the lamp light? Write yes or no.
3
In the conductor tester, a lamp lights. Is the material a conductor or an insulator? Write the word.
4
Look at the table in section 10.3. Is the copper coin a conductor? Write yes or no.
5
How many metals are in the table in section 10.3? Write the number.
6
Is pencil lead a metal, and is it a conductor? Write the two answers: yes or no for each, in the order metal then conductor.
7
Look at the table in section 10.4. Is the wooden stick a conductor or an insulator? Write the word.
8
Fill in the gap: electrical wires have a ___ coating that is an insulator. Write the word.
9
Which part of a switch is usually made of plastic: the metal contacts or the handle? Write the word.
10
Explain why a switch needs both a conductor and an insulator. Write one sentence.

Total 15 marks. Allow about 15 minutes.

Exercise 10X  Practice test questions

1
FIn a series circuit, a switch is closed. Does the lamp light? Write yes or no.[1 mark]
2
FIn a series circuit, a switch is open. Does the lamp light? Write yes or no.[1 mark]
3
FA material is placed between the clips of a conductor tester, and the lamp lights. Write the word: conductor or insulator.[1 mark]
4
FWrite the word for a material that does not let electricity flow through it, such as glass or plastic.[1 mark]
5
FWrite the name of one metal that is a good conductor of electricity.[1 mark]
6
FA wire is covered in plastic. Write the word for the plastic covering: conductor or insulator.[1 mark]
7
FWhich part of a switch completes the loop when the switch is closed? Write the words.[2 marks]
8
PSA steel paper clip and a plastic ruler are tested in the conductor tester. Which one makes the lamp light? Write the name.[2 marks]
9
RExplain why the plastic handle of a switch is an insulator. Write one sentence.[2 marks]
10
RA switch has metal contacts and a plastic handle. Write one sentence that says what each part is made of, and why.[3 marks]
← Chapter 9: Electricity and circuits

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