Year 8 Science · Unit 3 · Lesson 1

What Is Change in Matter?

Challenge Worksheet

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Date

Class

Learning Goals

Apply the physical/chemical change framework to human body chemistry.
Predict consequences using understanding of irreversible chemical change.
Use scientific terminology to construct a reasoned argument.

Go Deeper

What if…?

Scenario

Imagine that, starting from tomorrow, the human body could no longer carry out any chemical changes. Physical processes — moving, breathing air in and out, filtering blood — could still happen, but no new substances could be formed from existing ones inside any cell or organ. Every process that requires building a new molecule or breaking down a substance into something chemically different would simply stop.

Using what you know about chemical and physical change from this lesson, predict what would stop working first in the human body and explain why. Name at least three specific body processes that depend on chemical changes, and describe the consequence of each one failing. Use the terms chemical change, new substance, and irreversible in your answer.

Challenge 4 marks

Show What You Know

1. A student says: "Digesting food can't be a chemical change because it happens inside your body, not in a lab." Identify the flaw in this reasoning and explain the correct scientific view.

Challenge 3 marks

2. The Great Barrier Reef Marine Park Authority monitors coral colour changes carefully, distinguishing physical bleaching from chemical reactions in surrounding water. Explain why this distinction matters and what evidence scientists would look for to tell the two apart.

Challenge 3 marks

Wrap Up

In one sentence, what was the main idea of this lesson?