Year 7 Science · Unit 1 · Lesson 11

Unit Review + Working Scientifically

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Name
Date
Class

Learning Goals

Warm Up

Predict + reason

Scenario

A student is investigating whether the amount of light affects the growth rate of duckweed (Lemna minor) over 7 days. They set up three identical containers: one placed in bright light, one in dim light, and one in total darkness. They count the number of duckweed fronds in each container every day. All other conditions, water type, water volume, temperature, starting number of fronds, and container size, are kept the same.

(a) Write a hypothesis for this investigation using the "If … then … because …" structure.

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(b) Identify the independent variable in this investigation and name one controlled variable.

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Your Turn

Because… chain

The Q-H-M-R-D-C structure shows how a scientific investigation unfolds. Fill in the missing steps in the chain below.

A scientific question is identified: "How does light intensity affect duckweed growth?"
→
A method is planned: variables are listed, replicates are set up, safety is considered.
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Results are analysed: patterns, trends, and possible errors are identified in the data.
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Overall: a conclusion is reached that directly answers the original question using the results.

Show What You Know

1. A student changes both light intensity and water temperature in the same duckweed experiment. Explain why this makes it impossible to draw a valid conclusion about light intensity.

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2. In the duckweed investigation, a student sets up only one container per light condition (no replicates). Explain why replicates are important and what could go wrong without them.

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Wrap Up

In one sentence, what is the most important rule for designing a fair test?

HSCScience · Year 7 Science · Unit 1 · Lesson 11 · Apply Worksheet