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Rusting: an irreversible change

Lesson details

Learning outcome

I can describe rusting as an irreversible change, where a new material is formed.

Key learning points

  1. Rust is reddish brown in colour and has a rough texture.
  2. Rust is a new material that is formed when iron or steel is exposed to oxygen in the air and water.
  3. Rusting is an irreversible change whereby the original material cannot easily be recovered.
  4. Rusting materials can be looked at closely as they change over time, using observation skills.

Keywords

  • Rust - Rust is a reddish brown material which forms when iron or steel reacts with water and oxygen from the air.

  • Metal - Most metals are strong, hard and shiny materials.

  • Irreversible change - If a change is irreversible, it cannot be undone or changed back to its original state.

  • Observe - To observe is to look very closely and use other senses too.

Common misconception

Rusting happens immediately when the correct conditions are present and it only happens in water.

Teaching slides explain that rusting is not instant and that moisture from the air provides enough water for the process to take place.

Teacher tip

Encourage pupils to recognise that the water in the air is enough to provide the water needed for rusting and that items do not need to be submerged or partly in water to rust.

Equipment

Steel wool pads and bowls or saucers. Using a transparent centimetre square grid is optional.

Content guidance

Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Prior knowledge starter quiz

6 Questions

Q1.
What is a reversible change?

Correct answer: A change which can be undone or changed back to its original state.
A change which cannot be undone or changed back to its original state.

Q2.
Evaporation happens faster when the temperature is ...

Correct answer: warmer.
cooler.

Q3.
Match the reverse process of each change of state.

Correct Answer:melting,freezing

freezing

Correct Answer:condensation,evaporation

evaporation

Q4.
At temperatures between 0°C and 100°C, water is in state.

Correct Answer: liquid

Q5.
Which gas from the air is used during burning?

carbon dioxide
Correct answer: oxygen
air

Q6.
Match the process to the change of state.

Correct Answer:evaporation,when a liquid changes to a gas

when a liquid changes to a gas

Correct Answer:melting,when a solid changes to a liquid

when a solid changes to a liquid

Correct Answer:freezing,when a liquid changes to a solid

when a liquid changes to a solid

Correct Answer:condensation,when a gas changes to a liquid

when a gas changes to a liquid

6 Questions

Q1.
forms when iron is exposed to water and oxygen and is reddish brown in colour.

Correct Answer: Rust

Q2.
Which skills are needed to monitor changes in materials as they rust?

predicting
drawing
Correct answer: observation
modelling
concluding

Q3.
The changes observed in rusting materials ...

Correct answer: are often very slow.
are instant.
happen very quickly.

Q4.
What texture is rust?

smooth
Correct answer: rough
squishy
soft

Q5.
Which of these are needed for rust to form?

Correct answer: iron or steel
aluminium
Correct answer: oxygen
Correct answer: water
carbon dioxide

Q6.
Rusting is an change because it cannot be undone or changed back.

Correct Answer: irreversible

To help you plan your 5 science lesson on: Rusting: an irreversible change, download all teaching resources for free and adapt to suit your pupils' needs...