Year 7 Science · Unit 4 · Lesson 3
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Learning Goals
Put the steps in order
A student is investigating which paper towel brand soaks up the most water, but their steps are jumbled. Write the numbers 1 to 6 in the boxes to put them in a sensible order.
| Step | Order (1 to 6) |
|---|---|
| Record how much water each towel soaked up in a results table | |
| Ask the question: which brand soaks up the most water? | |
| Conclude which brand is best, using the evidence | |
| Predict which brand will win (make a hypothesis) | |
| Dip each towel in the same amount of water for the same time | |
| Plan a fair test: same size towel, same water, same time |
Real-world context
Mia wants to find out whether warmer water makes sugar dissolve faster. She fills three identical cups, each with 200 mL of water: one cold, one warm and one hot. She adds one level teaspoon of the same sugar to each cup, stirs each cup ten times, and uses a stopwatch to time how long the sugar takes to fully disappear. She writes her times neatly in a table.
(a) In Mia's investigation, what is the one thing she is changing on purpose, and what is the one thing she is measuring?
(b) List three things Mia kept the same to make her test fair, and explain why keeping them the same matters.
(c) Why is timing the sugar with a stopwatch a systematic observation, while just saying "it looked like the hot one was faster" would be a casual one?
1. A student tests which paper towel is best by dipping brand A in a big bowl for 10 seconds and brand B under a running tap for 3 seconds. Explain why this is not a fair test, then describe one change that would fix it.
2. Why is repeating a test three times and recording each result better than testing only once? Give two reasons.
Wrap Up
In one sentence, what was the main idea of this lesson?