3.11 Imagine something unseen13 April 2023

How does anyone know

what I look like?

Aims

• Learn how evidence from experiments and creative thinking can give us scientific explanations

• Learn early scientific ideas about matter

An ancient tale

• Six men were asked to work out what an elephant is like. But instead of looking at one, they had to touch it in the dark. The man who touched the tail thought it was a rope, and the man touched the trunk thought it was a snake. A tusk was mistaken for a spear, a leg a tree trunk and an ear for a fan. The man who touched the elephants side thought it was a wall.

Are particles real?

• If we cannot see these particles, how do we know they are real?

?

Early ideas

• Ancient Greeks though everything was made of four elements, and they were different because of their different proportions

• Fluids flow so their particles were rounded, solids had jagged particles

3.11 Imagine something unseenQuestions

1. Which of the two models of gases described on page 87 is used today?

2. What could the men in the Indian story on page 86 have done to collect accurate evidence about the elephant?

3. Why do scientists use models?

4. Suggest why the designers of large buildings use models to check their designs before building work starts.

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3.11 Imagine something unseen Questions

5. Why do gases expand to fill their container? Use the model of gas particles that push each other away in your explanation.

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3.11 Imagine something unseenFor your notes

Scientists use models to explain things that are observed.

The same thing can be explained by different models.

Scientists will change to using a different model if someone comes up with one that explains things better.

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