Lesson 3 of 4 · Scientific Argument

Experiment⭐ 30 XP

Sample Size and Bias

🧪Lab Brief #3

Scientific Argument.

🎯 Your mission

Run the experiment. Find out what really happens.

⚡ The twist

Nature loves to surprise the careful watcher.

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Mind = Blown

🔬 The more you look, the more nature shows you.

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Make a hypothesis first

Before you start: write down what you think will happen, and why.

What You'll Learn

A conclusion is only as good as the sample it came from. Too small a sample is dominated by chance; a sample drawn from the wrong group is biased no matter how large. Both faults produce confident, wrong answers.

Key Words

Tap a word to see its definition.

Materials Needed

tape measure
notebook
calculator

Safety First

Have an adult check your set-up before you start, and tidy everything away afterwards.

Steps

Step 1 — Read

Read the explanation above and note the two key terms before you start.

Step 2 — Do

Estimate the mean height of your year group from a sample of five, then twenty, then the basketball team. Compare all three with the true mean and name the fault in the third.

Step 3 — Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 — Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Check Your Understanding

Question 1

1 of 2

Sampling only the basketball team to estimate year-group height introduces:

How sure are you going to be?😐 maybe

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Where you see this in real life

This shows up in your everyday life more than you'd think.

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Stretch Challenge

Try this in real life this week.

Try one experiment in real life this week — even a tiny one.

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For the dinner table

“What's the most surprising thing you learned today?”

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Next Smart Experiment

We'll pick an experiment that matches exactly how you're thinking right now.

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