Science · 4th Grade

Active learning ideas

Melting and Freezing

Active learning works well for melting and freezing because these concepts rely on observable changes in matter over time, which students must witness, measure, and explain. Hands-on experiments and structured discussions help students connect particle-level behavior to real-world phenomena they can see and touch.

• Common Core State Standards
• 2-PS1-4

• 15–35 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Progettazione (Reggio Investigation)
• 35 min · Small Groups

Progettazione (Reggio Investigation): Melting Race

Give each group small samples of ice, butter, and chocolate at room temperature. Students predict which will melt first when placed in warm water, then observe and record actual melting order. Groups compare predictions with results and discuss what that tells them about each substance.

Explain what happens to the particles of a substance during melting.

Facilitation Tip

During Investigation: Melting Race, provide identical containers and thermometers so students focus on the variable of material rather than conditions.

What to look for

Provide students with a small cup containing ice cubes and another with a small amount of butter. Ask them to observe both over 5 minutes and write: 1. Which substance melted first and why? 2. What temperature change caused this to happen?

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

Activity 02

• Think-Pair-Share
• 15 min · Pairs

Think-Pair-Share: What Is a Melting Point?

After the investigation, ask: 'Why does ice always melt at the same temperature, no matter how big the piece is?' Partners discuss, then share ideas with the class. Guide students to the understanding that melting point is a property of the substance, not the amount.

Compare the energy changes involved in melting versus freezing.

Facilitation Tip

During Think-Pair-Share: What Is a Melting Point?, circulate and listen for student pairs to use the term 'melting point' correctly before sharing with the class.

What to look for

Present students with a chart showing three substances (e.g., water, chocolate, wax) and their known melting points. Ask: 'If you placed all three in a warm room, which would melt first? Which would melt last? Explain your reasoning.'

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

Activity 03

• Experiential Learning
• 30 min · Individual

Observation Journal: Freezing Water Over Time

Students record observations of water placed in a freezer at regular intervals (or watch time-lapse footage). They sketch what they observe and label changes, then write an explanation of what is happening to the particles at each stage.

Predict the melting point of an unknown solid based on its behavior.

Facilitation Tip

During Observation Journal: Freezing Water Over Time, remind students to record both temperature and physical state changes every two minutes.

What to look for

Pose the question: 'Imagine you have a block of ice and a block of frozen juice. If you put them both outside on a warm, sunny day, what do you predict will happen? How does temperature play a role in your prediction?' Facilitate a class discussion on their ideas.

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

Activity 04

• Gallery Walk
• 25 min · Small Groups

Gallery Walk: Melting and Freezing in Nature and Industry

Post stations with images and captions showing melting and freezing in real contexts: glaciers melting, steel being poured, candle wax solidifying, roads icing overnight. Students identify the process at each station and connect it to the energy change involved.

Explain what happens to the particles of a substance during melting.

Facilitation Tip

During Gallery Walk: Melting and Freezing in Nature and Industry, assign roles like reader, recorder, and reporter to keep all students engaged.

What to look for

Provide students with a small cup containing ice cubes and another with a small amount of butter. Ask them to observe both over 5 minutes and write: 1. Which substance melted first and why? 2. What temperature change caused this to happen?

• Understand
• Apply
• Analyze
• Create
• Relationship Skills
• Social Awareness

A few notes on teaching this unit

Start with simple, repeatable experiments so students experience the same phase change multiple times. Avoid teaching melting and freezing as abstract concepts; instead, ground them in everyday examples like ice cream melting or puddles freezing. Research shows that emphasizing the reversibility of these processes helps students grasp the conservation of matter during phase changes.

Students will accurately describe how heat energy changes the arrangement of particles during melting and freezing. They will use evidence from their investigations to explain why melting points are consistent for a substance and how size or conditions affect melting time.

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Watch Out for These Misconceptions

• During Investigation: Melting Race, watch for students who predict larger pieces of ice will melt faster because they assume the melting point changes with size.

  Have students measure the temperature of melting ice cubes of different sizes in identical conditions, then discuss why the temperature remains constant while the time to melt varies.

• During Investigation: Melting Race, watch for students who confuse melting with dissolving when comparing ice and butter.

  Ask students to describe what happens to each substance at the particle level; highlight that melting changes the state of the substance, while dissolving involves mixing.

• During Observation Journal: Freezing Water Over Time, watch for students who use 'freezing' to describe any temperature drop, not the phase change at 0°C.

  Prompt students to identify the exact moment when water changes from liquid to solid, emphasizing that freezing occurs only at the freezing point.

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Methods used in this brief

• Progettazione (Reggio Investigation)
• Think-Pair-Share
• Experiential Learning
• Gallery Walk