Science · Grade 2

Active learning ideas

Heating and Cooling Materials

Active learning helps students see that heating and cooling are reversible changes they can control and measure, not mysterious forces. When children feel chocolate soften in their hands or watch ice refreeze, they connect abstract ideas to personal experience, building lasting understanding.

• Ontario Curriculum Expectations
• 2-PS1-4

• 25–40 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 25 min · Small Groups

Prediction Chart: Chocolate Melting

Students predict what happens when chocolate melts in warm water, then observe and draw changes on a class chart. Cool samples in ice water and note reversal. Discuss predictions versus results.

Analyze how heating affects the state of chocolate.

Facilitation Tip

During Prediction Chart: Chocolate Melting, give each pair one chocolate square so students feel the warming process together and discuss their predictions aloud.

What to look for

Provide students with a small piece of chocolate. Ask them to describe in writing or drawing what happens when they hold it in their hands for one minute, and then describe what happens when they place it in a cool place afterward.

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

Activity 02

• Experiential Learning
• 35 min · Pairs

Compare and Test: Ice versus Clay

Provide ice cubes and clay balls. Heat both gently with warm water or hands, observe differences, then cool. Groups record states before, during, and after in tables.

Compare the effects of heating ice and heating clay.

Facilitation Tip

For Compare and Test: Ice versus Clay, set timers to keep observations focused and prevent melting ice from sitting too long before comparisons begin.

What to look for

Present students with two scenarios: 'Imagine you leave a crayon in a sunny window and it melts. Can you get the crayon back?' and 'Imagine you freeze water and it turns into ice. Can you get the water back?' Ask students to explain why some changes can be undone and others might be more difficult.

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

Activity 03

• Experiential Learning
• 40 min · Whole Class

Outdoor Observation: Butter in Sun

Students predict butter changes in sunlight, place samples outside, check every 10 minutes, and sketch observations. Return indoors to cool and note reversal.

Predict what will happen to butter when it is left in the sun.

Facilitation Tip

During Outdoor Observation: Butter in Sun, have students sketch the butter’s appearance every five minutes to build a clear timeline of change.

What to look for

During an experiment with ice, ask students: 'What do you observe happening to the ice as it sits on the warm tray? What is this change called?' Then, after placing the melted water in a freezer, ask: 'What do you observe happening to the water now? What is this change called?'

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

Activity 04

• Experiential Learning
• 30 min · Pairs

Cooling Relay: Material Recovery

Set stations with melted items like crayons or soap. Pairs race to cool them back to solid, timing recovery and sharing methods that work best.

Analyze how heating affects the state of chocolate.

Facilitation Tip

In Cooling Relay: Material Recovery, place cooled samples in labeled spots so students can quickly see which materials returned to their original state.

What to look for

Provide students with a small piece of chocolate. Ask them to describe in writing or drawing what happens when they hold it in their hands for one minute, and then describe what happens when they place it in a cool place afterward.

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

A few notes on teaching this unit

Teachers should model curiosity by asking questions like 'What do you think will happen next?' rather than giving answers immediately. Avoid telling students whether a change is reversible before they observe it; let the experiments guide their conclusions. Research shows that when students articulate their own predictions and then test them, they remember the science longer.

Successful learning looks like students predicting changes, recording observations with words or drawings, and explaining reversibility using evidence from their experiments. By the end, they should confidently state that some changes can be undone and describe how they know.

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Watch Out for These Misconceptions

• During Prediction Chart: Chocolate Melting, watch for students who believe the melted chocolate is gone forever.

  Have students hold a cooled piece of chocolate next to the melted one and describe what they see. Ask them to draw arrows showing how the chocolate moved from solid to liquid and back.

• During Compare and Test: Ice versus Clay, watch for students who assume all solids will act the same way when heated.

  Ask students to point to the clay and ice in their notes, then circle the words 'melted' or 'softened' to show which change happened to each. Peer sharing of these notes corrects the idea that all solids change identically.

• During Cooling Relay: Material Recovery, watch for students who think cooling can never undo heating.

  After cooling, have students measure the time it took for each material to return to its original shape, then vote as a class on whether cooling can undo heating. Charts tracking these times provide evidence for class discussion.

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Methods used in this brief

• Experiential Learning