New
New
Year 5

More reversible changes

I can demonstrate how mixing and dissolving are reversible changes

New
New
Year 5

More reversible changes

I can demonstrate how mixing and dissolving are reversible changes

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Lesson details

Key learning points

  1. If a change is reversible, it can be undone or changed back to its original state.
  2. A mixture is material that contains two or more different substances, which can be physically separated.
  3. When a soluble solid dissolves, it is broken down to become so tiny we can no longer see it, but it is still there.
  4. Dissolving is a reversible process. Evaporation can be used to recover soluble solids from solutions.

Keywords

  • State - The three common states of matter are solid state, liquid state and gas state.

  • Recover - To recover is to get back something that had changed or was taken away.

  • Reversible - If a change is reversible, it can be undone or changed back to its original state.

  • Dissolve - If a solid dissolves in a liquid, it mixes so completely with the liquid that it cannot be seen.

  • Mixture - A mixture can be physically separated.

Common misconception

Changes in state and dissolving and mixing are not reversible processes.

Teaching slides will show which processes can be used to reverse state changes and dissolving. This will be explored and embedded during the practice tasks.

Encourage children not to say that a solid has disappeared when it has dissolved but to recognise that it has broken down to become so tiny we can no longer see it, but it is still there.
Teacher tip

Equipment

Equipment and materials for making lemonade and then to separate the original materials from a sample of it. See additional materials.

Content guidance

  • Risk assessment required - equipment
  • Exploration of objects

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), 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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6 Questions

Q1.
Which of these are states of matter?
Correct answer: solid state
ice state
Correct answer: gas state
water state
Q2.
At what temperature does liquid water change to ice?
An image in a quiz
Correct answer: 0°C
100°C
80°C
50°C
Q3.
Match the name of the process to the description:
Correct Answer:melting,when a substance changes from its solid state to its liquid

when a substance changes from its solid state to its liquid

Correct Answer:dissolving,when a solid is broken into very small pieces and disappears

when a solid is broken into very small pieces and disappears

Q4.
What happens when you stir sand in water?
An image in a quiz
the water evaporates, leaving the sand
the sand dissolves in the water
Correct answer: the sand makes a mixture with the water
Q5.
A substance dissolves in a liquid.
An image in a quiz
Correct Answer: soluble
Q6.
True or false? You can recover a dissolved solid from a solution by filtration.
An image in a quiz
true
Correct answer: false

6 Questions

Q1.
If a change is reversible …
An image in a quiz
Correct answer: it can be undone or changed back to its original state.
a new material is produced.
it cannot be undone or changed back to its original state.
Q2.
What process can be used to reverse evaporation?
Correct Answer: condensation, condensing, condense
Q3.
A mixture is material that contains two or more different substances, which can be physically ...
mixed.
undone.
reversed.
Correct answer: separated.
Q4.
What happens to a soluble solid when it dissolves?
An image in a quiz
It changes into the liquid.
Correct answer: It is broken down to become so tiny we can no longer see it.
It melts so we can no longer see it.
Q5.
Is making a mixture a reversible or irreversible process?
Correct answer: reversible
ireversible
Q6.
How can you recover dissolved solids from a solution?
An image in a quiz
condensation
Correct answer: evaporation
filtering
freezing
Q1 Cagkan Sayin/Shutterstock.com

Additional material

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