Science · Year 5

Active learning ideas

Changing States: Melting and Freezing

Active learning helps students grasp the difference between reversible and irreversible changes by making abstract ideas concrete. Through hands-on experiments with melting, freezing, and reactions, students see firsthand how some changes can be reversed while others cannot.

• National Curriculum Attainment Targets
• NC-KS2-Science-Y5-PCM-3

• 20–60 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Experiential Learning
• 45 min · Small Groups

Predict-Observe-Explain: The Mystery Reactions

Provide students with several scenarios, such as mixing vinegar and milk or melting chocolate. Students predict if the change is reversible, observe the reaction in small groups, and then write an explanation using evidence like 'no new material was formed' or 'a gas was produced'.

Explain what happens to the particles of a substance when it melts or freezes.

Facilitation Tip

During Predict-Observe-Explain, pause after predictions to let students discuss their ideas in pairs before revealing the reactions to deepen engagement.

What to look for

Provide students with a diagram showing a solid turning into a liquid. Ask them to label the process (melting) and write one sentence describing what is happening to the particles. Then, ask them to name one common substance that melts.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Stations Rotation
• 60 min · Small Groups

Stations Rotation: Recovery Lab

Students visit stations where a change has already occurred, such as salt dissolved in water or a burnt piece of paper. Their task is to brainstorm and, where possible, attempt a method to reverse the change, such as using evaporation or filtration, to see which materials can be recovered.

Analyze how temperature affects the rate at which ice melts.

Facilitation Tip

In the Recovery Lab, set up stations so students rotate in small groups to encourage peer teaching and shared observation of reversible changes.

What to look for

Show students three beakers, one with ice cubes, one with water, and one with steam. Ask: 'Which beaker shows a substance that has frozen? Which shows a substance that has melted? Which shows a substance that is neither melting nor freezing?'

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Activity 03

• Think-Pair-Share
• 20 min · Pairs

Think-Pair-Share: The Kitchen Scientist

Students think of three changes that happen during cooking, such as frying an egg, boiling water, or making toast. They pair up to categorize these as reversible or irreversible and then share their reasoning with the class, focusing on whether a new substance was created.

Predict whether a substance will melt or freeze at a given temperature.

Facilitation Tip

In Think-Pair-Share, assign specific roles (recorder, reporter) to ensure all students contribute and stay accountable during discussions.

What to look for

Pose the question: 'Imagine you leave a glass of water outside on a very cold day. What will happen to the water? How do you know? What if you bring it back inside?' Encourage students to use the terms melting, freezing, and reversible.

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

A few notes on teaching this unit

Experienced teachers approach this topic by building on students’ everyday experiences, such as ice melting into water or chocolate softening in a pocket. Use real substances like wax or ice to make the concepts tangible, avoiding abstract diagrams until students have solidified their understanding. Research shows that concrete examples reduce misconceptions about states of matter and reinforce the idea that changes in state are physical, not chemical. Avoid overemphasizing heat as the sole cause of change, since cooling is equally important to reversing the process.

Students will confidently identify reversible changes like melting and freezing, explain why dissolving or mixing can be undone, and distinguish these from irreversible changes by describing the materials before and after each process. They will use accurate vocabulary and support their reasoning with evidence from their investigations.

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Watch Out for These Misconceptions

• During Predict-Observe-Explain: The Mystery Reactions, watch for students assuming that any reaction requiring heat is irreversible.

  Use the wax or chocolate melting activity to demonstrate that heating can reverse the change when cooled again, contrasting this with the vinegar and bicarbonate reaction which produces a new gas.

• During Station Rotation: Recovery Lab, watch for students thinking that gases produced in reactions have disappeared.

  Have students capture the gas from the vinegar and bicarbonate reaction in a balloon and observe that the balloon inflates, showing the gas still exists and can be measured by size.

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Methods used in this brief

• Experiential Learning
• Stations Rotation
• Think-Pair-Share