Year 8 Science · Unit 4 · Lesson 19
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Learning Goals
Spot the missing step
Each student below has skipped one of the four steps. Write which step they missed.
| What the student did | Step missed |
|---|---|
| Said 'the shed gets hot' and immediately drew a diagram of sunlight hitting the roof. | |
| Measured the temperature carefully every hour, then announced the model was finished. | |
| Explained the mechanism in words but never produced a diagram, object or equation. | |
| Built a neat labelled model that fitted the shed, and never checked it anywhere else. |
Build a model, four steps
A student notices that the grass under one particular tree in the park is always thin and patchy, while grass a few metres away is thick. Work the four steps for this phenomenon.
1. Step 1. Describe the phenomenon precisely. Say what differs, where, and compared with what.
2. Step 2. Propose a hidden mechanism that would force thin grass under that tree.
3. Step 3. Describe the model you would build. What would your diagram show, and what would each label name?
4. Step 4. Give a test case your model has not seen, state what it predicts there, and state one result that would show your mechanism is wrong.
5. A student writes: 'My model is a theory because it explains the patchy grass really well.' Explain why a scientist would not accept that yet.
6. Give one reason a model that fails its test case is still useful to the scientist who built it.
Wrap Up
Write the one question you should always ask yourself before you believe your own model.