Random Error Scatters, Systematic Error Shifts

Lab Brief #3

🎯 Your mission

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

⚡ The twist

Nature loves to surprise the careful watcher.

What you'll learn

Random error scatters readings either side of the true value, so averaging more repeats narrows the spread and improves precision. Systematic error shifts every reading the same way, so the mean of a thousand readings from a balance reading 2 g high is still 2 g wrong — repeating changes nothing at all. The two faults are fixed by different actions: repeats for the first, calibration against a known standard for the second, which is why precision and accuracy are reported separately.

Key words

random error
Unpredictable scatter either side of the true value, reduced by averaging repeated readings.
calibration
Checking an instrument against a known standard and correcting it, the only fix for systematic error.

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

balance
known standard mass
test object
calculator

⚠️ Safety first

Set the balance well back from the bench edge so the masses cannot roll off.

Step 1 of 4 · Read

Think about what you just learned: say what "random error" and "calibration" mean in your own words before you start.

Step 2 of 4 · Do

Weigh the same object ten times on a balance you have deliberately zeroed 2 g high, and ten times on a correctly zeroed one. Calculate the mean and spread for both sets and state which fault repeats fixed and which they did not.

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 3

Averaging more repeats reduces:

How sure are you?😐 maybe

Question 2 of 3

A balance reading 2 g high produces a mean over 1,000 readings that is:

How sure are you?😐 maybe

Question 3 of 3

The only fix for systematic error is:

How sure are you?😐 maybe

Mind = blown

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

Nice work!

You got 0 of 3 right.

Next: Percentage Uncertainty Rewards Measuring Something Bigger All lessons

🎯

Next Smart Experiment

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

✨ 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?”

📊Share card

Share this experiment

Send it to a parent who's looking for a 10-minute kitchen science win.

Random Error Scatters, Systematic Error Shifts

Next Smart Experiment

Share this experiment

Random Error Scatters, Systematic Error Shifts

Done with science? Try something else

Your Cart (0)