Heat Changes Materials

Overview

Students investigate the observable properties of icing sugar, granulated sugar, flour and egg white before and after gentle heating. They make predictions, observe teacher-controlled demonstrations, record evidence in tables and explain that adding heat can change materials, although not every material visibly changes state.

Learning intentions

• WALT identify observable properties of solids and liquids.
• WALT explain that heat energy can cause changes in materials.
• WALT pose a question, make a prediction and participate in a fair investigation.
• WALT record observations in a table and identify patterns in the evidence.
• WALT use scientific vocabulary to discuss results.

Success criteria

• I can describe a material using observable properties such as shape, texture, colour and flow.
• I can classify each sample as a solid or liquid before heating.
• I can record what I observe before and after heating without guessing.
• I can explain that heat energy was added and describe any change observed.

Vocabulary

solid, liquid, properties, heat energy, melt, change of state, observe, predict, evidence, fair test, variable, texture, flow

Curriculum links

• Observable properties of solids and liquids, and how adding heat energy can lead to a change of state.
• Sources and transfer of heat energy, including measuring or observing changes caused by heat.
• Posing questions, making predictions and identifying relationships from observations.
• Planning and conducting a safe, fair investigation.
• Organising observations in tables and identifying patterns.

Safety

• The teacher operates the candle and handles all heated equipment; students remain seated behind the safety boundary.
• Use a stable candle holder on a heatproof tray, keep hair and loose clothing secured, and keep water available for emergencies.
• The teacher uses small amounts of materials and allows samples and equipment to cool before students view them closely.
• Students do not touch the candle, flame, hot containers or heated samples.
• Students do not taste any materials. Egg white is not consumed and is disposed of after the investigation.
• Remind students to follow instructions, report spills or discomfort immediately, and wash hands after the activity.

Lesson structure (45 minutes)

1. 0–5 min · Hook and WALT. Open with the hook and learning intention slides showing a before-and-after image of an ice cube or melted chocolate and ask, “What can heat do to a material?” Students share an observation and a prediction with a partner.

2. 5–10 min · Properties and fair test. Use the solids, liquids and fair-test slides to review that solids hold their shape while liquids flow and fill the bottom of a container; discuss the question, “What happens to these materials when gentle heat is added?” Students help identify the independent variable (heating), the dependent variable (observable change), and controls: same small amount, same type of container, similar heating time and teacher-controlled flame.

3. 10–15 min · Predict. Distribute the Heat Changes Materials investigation sheet. Students examine sealed or covered sample containers without touching the contents, record initial properties and complete the prediction table.

Material	Before heating: solid/liquid and properties	Prediction after heating
Icing sugar
Granulated sugar
Flour
Egg white

Students may predict “no visible change”, “softens”, “darkens”, “bubbles” or “becomes more liquid”.

4. 15–28 min · Teacher investigation. Place small samples in separate heatproof metal containers and gently heat one at a time over the candle, narrating each step. Groups of 4–5 observe from a safe distance and record changes such as melting, clumping, browning, thickening, bubbling, drying or no obvious change. Pause between samples for students to share precise observations. Do not imply that every sample must change state.

5. 28–35 min · Record and represent data. Students complete the observation table on the Heat Changes Materials investigation sheet and use a simple symbol or labelled drawing for each sample. If appropriate, the teacher creates a class tally or column graph showing the number of samples with a visible change.

Material	Before heating	After heating	Visible change? What evidence?
Icing sugar
Granulated sugar
Flour
Egg white

6. 35–41 min · Discuss evidence. Return to the investigation discussion slides. Ask: “Which material changed most visibly?”, “Did any material change state?”, “What evidence supports your answer?”, “Was egg white a solid or liquid before heating?”, and “Why was it important to keep the amount and heating method similar?” Clarify that sugar may melt or darken, flour may brown or clump, icing sugar may show little visible change, and egg white may thicken or become solid when heated. These are observations; a visible change is not required for every material.

7. 41–45 min · Plenary and exit check. Students complete the final prompt on the Heat Changes Materials investigation sheet: “Heat energy was added. One change I observed was ____. One material that did not visibly change was ____. This investigation was fair because ____.” Invite two students to share evidence-based conclusions.

Resources

• the Heat Changes Materials slide deck
• the Heat Changes Materials investigation sheet
• Icing sugar, granulated sugar and flour
• Egg white in a labelled container
• Four small heatproof metal containers or spoons
• Stable candle holder, candle, heatproof tray and water for emergencies
• Goggles for the teacher and optional student eye protection
• Timer, board and markers
• Handwashing supplies and waste container

Assessment

• Listen for accurate classification of solids and liquids and correct use of “observe” versus “predict”.
• Check prediction and observation tables for specific, observable evidence rather than unsupported explanations.
• Use the exit response to assess understanding that heat energy can cause different changes and that a fair test keeps key conditions the same.

Differentiation

• Provide picture-supported vocabulary, a word bank and sentence starters: “Before heating, it was…”, “I observed…”, and “The evidence is…”.
• Pair students strategically within groups of 4–5; assign roles such as observer, recorder, equipment watcher and reporter. Students may draw observations or dictate responses.
• Read the worksheet aloud, enlarge the tables and provide reduced writing demands for students with literacy, motor or attention needs. Keep all students behind the safety boundary.
• For advanced learners, ask them to distinguish a change of state from another observable change, explain which evidence supports their conclusion, and propose one improvement for repeating the investigation fairly.