Repeats, Means and Reliability

Lab Brief #5

🎯 Your mission

Predict it first. Then prove yourself right (or wrong).

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

One measurement can be wrong by accident. Taking three or more repeats and using the mean reduces the effect of random scatter, and comparing the repeats tells you how much to trust the mean.

Key words

repeat reading
One of several measurements of the same quantity under the same conditions.
reliable
Producing similar values when the measurement is repeated.

Make a hypothesis first

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

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

paper
scissors
paper clips
stopwatch
metre rule

Get ready

⚠️ Safety first

Use scissors carefully and cut on a flat surface.
Drop from a stable step with someone spotting, never from a chair.

Step 1 of 4 · Read

Think about what you just learned: say what "repeat reading" and "reliable" mean in your own words before you start.

Step 2 of 4 · Do

Time how long a paper spinner takes to fall, five times. Calculate the mean and the range. Then do it once only and explain to a partner why the single value is less trustworthy.

Step 3 of 4 · Observe

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

Step 4 of 4 · Record

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

Question 1 of 2

Taking repeats and averaging mainly reduces:

How sure are you?😐 maybe

Question 2 of 2

Results that are close together when repeated are described as:

How sure are you?😐 maybe

Mind = blown

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

Nice work!

You got 0 of 2 right.

Next: Reading Someone Else's Data All lessons

🎯

Next Smart Experiment

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✨ More to explore

🌍 Where you see this in real life: This shows up in your everyday life more than you'd think.

🏆 Stretch challenge (try it this week): Try one experiment in real life this week — even a tiny one.

👨‍👩‍👧 For the dinner table: “What's the most surprising thing you learned today?”

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