Lesson 2: What are reversible changes?

This Year 5 reversible and irreversible changes lesson explores which changes to materials can be reversed and which cannot. Pupils investigate different ways of reversing changes, including evaporation, sieving, filtering, melting and cooling, before comparing these with a chemical change that produces a new material.

The lesson directly supports the Year 5 Science National Curriculum requirement to demonstrate that dissolving, mixing and changes of state are reversible changes. Pupils build on their previous learning about dissolving and states of matter to explain how materials can be separated and recovered.

What is a reversible change?

Pupils learn that a reversible change can be undone so that the original materials can be recovered. They revisit dissolving from the previous lesson and observe how evaporation can be used to separate salt from a salt solution, before exploring a range of other reversible changes.

Through a carousel of practical activities, pupils investigate dissolving salt in water, separating rice and flour using a sieve, separating ground coffee from water by filtering and changing butter between solid and liquid states. They consider which method can be used to reverse each change and explain what is happening using scientific vocabulary.

What is the difference between reversible and irreversible changes?

Pupils compare reversible changes with a change that cannot easily be reversed. In the magic glove activity, vinegar and bicarbonate of soda are mixed and pupils observe carbon dioxide gas being produced, causing a glove to inflate. They record their observations and discuss why creating new substances is evidence of an irreversible change.

Pupils then apply their understanding to familiar examples, considering whether changes such as frying an egg, making toast, dissolving salt and melting chocolate are reversible or irreversible.

What’s included in this Year 5 reversible and irreversible changes lesson?

• Launchable teaching slides for whole-class teaching
• Detailed lesson plan with National Curriculum coverage, teacher knowledge, vocabulary, misconceptions, safety guidance and assessment questions
• Reversible changes worksheet
• Five-station carousel exploring dissolving, the water cycle, sieving, filtering and changes of state
• Teacher demonstration showing how evaporation can separate salt from a solution
• Magic glove instructions and observation sheet for exploring an irreversible change
• Practical sieving and filtering activities for separating mixtures
• Salt crystal instructions for observing how salt can be recovered from a solution
• Continuous provision and further challenge ideas exploring reversible and irreversible changes

Explore the full Year 5 Properties and Changes of Materials resources, or explore our Year 5 science scheme of work and resources.