Science · Year 5

Active learning ideas

Changes of State: Melting and Freezing

Active learning helps Year 5 students grasp changes of state by moving beyond abstract explanations to direct observation and experimentation. Hands-on activities make particle movement visible through measurable outcomes like freezing time and melting patterns, turning theory into evidence they can see and touch.

• ACARA Content Descriptions
• AC9S5U04

• 25–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 45 min · Pairs

Experiment: Salt vs Pure Water Freezing

Provide pairs with pure water and saltwater in identical containers; place in freezer and check hourly. Students record freezing times and temperatures, then graph results. Discuss why salt delays freezing.

Explain how adding heat changes the behavior of particles during melting.

Facilitation Tip

During Experiment: Salt vs Pure Water Freezing, circulate to ensure students measure the same volume of water and salt for fair comparison.

What to look for

Provide students with two scenarios: one describing ice melting into water, the other describing water freezing into ice. Ask them to write one sentence for each scenario explaining the role of temperature and particle movement.

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

Activity 02

• Stations Rotation
• 40 min · Small Groups

Stations Rotation: Melting Conditions

Set up stations with ice cubes on foil under different conditions: room temp, warm water bath, insulated wrap, and with salt. Groups rotate every 10 minutes, timing melts and noting particle clues like puddles forming.

Compare the energy changes involved in melting versus freezing.

Facilitation Tip

During Station Rotation: Melting Conditions, place a timer at each station so students can focus on recording melting times without losing track of their observations.

What to look for

Show students a video clip of chocolate melting. Ask: 'What is happening to the chocolate particles as heat is added? What is this process called?' Record student responses on a whiteboard.

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

Activity 03

• Experiential Learning
• 30 min · Whole Class

Whole Class: Temperature Graphing

Melt ice in a shared beaker while class logs temperature every minute on a shared chart. Predict plateaus during phase change; review graph to explain constant temperature despite added heat.

Predict how impurities might affect the melting point of a substance.

Facilitation Tip

During Whole Class: Temperature Graphing, model how to label axes and plot points accurately before students begin working independently.

What to look for

Pose the question: 'Imagine you add a tablespoon of salt to a glass of water and then put it in the freezer. How might the salt affect the time it takes for the water to freeze compared to plain water? Why?' Facilitate a class discussion using student predictions.

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

Activity 04

• Experiential Learning
• 25 min · Individual

Individual: Predict and Test Chocolate

Students predict melting times for chocolate pieces at varied spots: hand, desk, fridge. Test, time, and journal particle explanations with sketches.

Explain how adding heat changes the behavior of particles during melting.

Facilitation Tip

During Individual: Predict and Test Chocolate, ask students to record both their prediction and the actual melting time to emphasize the importance of evidence-based reasoning.

What to look for

Provide students with two scenarios: one describing ice melting into water, the other describing water freezing into ice. Ask them to write one sentence for each scenario explaining the role of temperature and particle movement.

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

A few notes on teaching this unit

Teachers should anchor instruction in everyday materials students recognize, like ice and chocolate, to make particle theory concrete. Emphasize reversibility by having students refreeze melted materials, which combats the misconception that changes of state create new substances. Avoid rushing to explanations; let students wrestle with observations first, then guide them to connect evidence to particle movement.

Successful learning looks like students using precise vocabulary to describe melting and freezing, explaining particle behavior in real-world examples, and applying their understanding to predict outcomes in new contexts. They should connect temperature changes to observable changes in state and justify predictions with evidence from experiments.

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Watch Out for These Misconceptions

• During Experiment: Salt vs Pure Water Freezing, watch for students who believe the salt changes the water into a new substance.

  Use the experiment’s reversibility test—refreezing the melted salt water—to show that it returns to ice, proving the substance remains water with salt dissolved in it. Have students compare the mass of the water before and after freezing to reinforce that mass is conserved.

• During Station Rotation: Melting Conditions, watch for students who assume all substances melt at the same temperature.

  Have students compare melting times across stations using the same heat source, then ask them to rank substances by melting point. Use a class chart to compile data, highlighting differences in melting times as evidence of varying melting points.

• During Whole Class: Temperature Graphing, watch for students who think particles stop moving completely when frozen.

  Use the graphing activity to connect cooling curves to particle movement: as the line flattens, point out that particles are vibrating in place, not stopping. Have students act out particle movement during the graphing discussion to visualize this concept.

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Methods used in this brief

• Experiential Learning
• Stations Rotation