Science · 1st Grade

Active learning ideas

Changing Materials: Heating and Cooling

First graders learn best when they can see, touch, and test their ideas in real time. This topic comes to life when students observe materials changing before their eyes, making abstract concepts like reversible and irreversible changes concrete and memorable.

• Common Core State Standards
• 2-PS1-4

• 20–30 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Inquiry Circle
• 30 min · Small Groups

Inquiry Circle: Ice Cube Investigation

Small groups receive ice cubes and predict what will happen if the ice is left in a cup on the desk, recording which properties they think will change. They observe over 20 minutes, noting temperature, state, and appearance changes. After the ice melts, they predict what would happen if they could freeze the water again and discuss whether they think this is a reversible change.

Explain how heating can change the state or properties of a material.

Facilitation Tip

During Ice Cube Investigation, ask students to predict what will happen to the ice when left in the sunlight and then test their predictions by weighing the melted water in the same container.

What to look for

Show students pictures of common items like an ice cube, a chocolate chip, and a piece of toast. Ask them to point to or say whether heating would make it melt or change permanently, and whether cooling would make it freeze or change permanently. Record their responses.

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Activity 02

• Gallery Walk
• 25 min · Individual

Gallery Walk: Reversible or Not?

Post photos of eight change events around the room: ice melting, butter melting, wood burning, an egg cooking, chocolate melting, paper tearing, clay being shaped, and bread toasting. Students walk around and for each photo indicate whether they think the change is reversible or not, writing one reason for their choice.

Compare the effects of heating and cooling on different substances.

Facilitation Tip

During Gallery Walk: Reversible or Not?, model how to use sentence stems like 'I see evidence that this change is reversible because...' to support students in explaining their thinking.

What to look for

Provide students with two index cards. On one card, they draw a picture of something that changes reversibly when heated or cooled. On the other card, they draw something that changes irreversibly. They should label each drawing.

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

Activity 03

• Think-Pair-Share
• 20 min · Pairs

Think-Pair-Share: What Changed and Can We Undo It?

Show students a melted crayon that hardened into a new shape. Ask what happened when it was heated, what happened when it cooled, and whether the original crayon still exists in some form. Students pair to construct an explanation, then share with the class. The teacher connects this to reversible changes where material composition has not changed.

Predict what might happen to a material if it is heated or cooled significantly.

Facilitation Tip

During Think-Pair-Share: What Changed and Can We Undo It?, circulate and listen for students to connect their observations from the Ice Cube Investigation to other materials, such as butter or bread.

What to look for

Ask students: 'Imagine you have a stick of butter and a raw egg. If you heat both, what happens? Which change can you undo, and which can you not undo? Why is it important for cooks to know the difference?'

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

Activity 04

• Simulation Game
• 20 min · Whole Class

Simulation Game: Prediction Chain

The teacher presents a series of heating and cooling scenarios using a photo sequence. Students predict the next state in the sequence, such as what a hot ice cube becomes, what frozen juice becomes when left out, and what melted chocolate becomes when cooled. After predicting each step, students classify the overall change as reversible or requiring more investigation.

Explain how heating can change the state or properties of a material.

Facilitation Tip

During Simulation: Prediction Chain, pause after each step to ask, 'What do you think will happen next, and why?' to encourage students to connect cause and effect.

What to look for

Show students pictures of common items like an ice cube, a chocolate chip, and a piece of toast. Ask them to point to or say whether heating would make it melt or change permanently, and whether cooling would make it freeze or change permanently. Record their responses.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

A few notes on teaching this unit

Teachers should focus on providing varied, hands-on experiences with a range of materials to avoid overgeneralizing changes to just melting or freezing. Avoid leading students toward the idea that all heating causes melting; instead, let their observations guide the discussion. Research shows that young children learn through repetition and comparison, so revisiting reversible and irreversible changes in different contexts deepens understanding and corrects misconceptions.

Students will confidently identify at least three examples of reversible changes and three irreversible changes after these activities. They will use evidence from their investigations to explain why some changes can be undone while others cannot, using clear, kid-friendly language.

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Watch Out for These Misconceptions

• During Ice Cube Investigation, watch for students who assume all materials melt when heated.

  Use the investigation to introduce materials like bread or wood, which do not melt but instead burn or harden. Ask, 'What happened to the bread? Can we get the raw dough back? Why or why not?'

• During Gallery Walk: Reversible or Not?, watch for students who assume all changes caused by heating or cooling can be reversed.

  Have students compare their ice cube observations to the baked cookie example on the gallery walk. Ask, 'Can you undo baking a cookie? Why or why not?' to prompt discussion about irreversible changes.

• During Ice Cube Investigation, watch for students who think the melted ice cube has disappeared.

  Weigh the ice cube before melting and the water after to show the same amount of material remains. Ask, 'Where did the ice go? Is it still here? How do you know?'

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Methods used in this brief

• Inquiry Circle
• Gallery Walk
• Think-Pair-Share
• Simulation Game