Year 8 Science · Unit 4 · Lesson 8

Accuracy, Precision and Reliability

Foundation Worksheet

Name

Date

Class

Learning Goals

Define accuracy, precision, random error, systematic error and range.
Distinguish between precise-but-inaccurate (systematic error) and accurate-but-imprecise (random error) results.
Explain how repeating trials reduces random error but not systematic error.

Warm Up

Match each term to its definition

Draw a line connecting each term on the left to its correct definition on the right. Or write the matching letter next to each term.

Term	Your answer	Definition
Accuracy		A. Unpredictable variation in measurements that scatters results — reduced by averaging repeated trials.
Precision		B. The difference between the highest and lowest values in a dataset.
Random error		C. How close a measurement is to the true or accepted value.
Systematic error		D. How close repeated measurements are to each other — about consistency, not correctness.
Range		E. An error that biases every measurement in the same direction — not fixed by repeating trials.

Your Turn

Sort it!

Write each measurement scenario into the correct category. The true value for all examples is 100°C (boiling point of pure water).

5 readings: 99.8, 100.1, 100.0, 99.9, 100.2°C 5 readings: 97.1, 97.2, 97.0, 97.3, 97.1°C 5 readings: 99.5, 100.8, 98.9, 101.2, 99.7°C 5 readings: 94.0, 105.0, 93.5, 106.1, 92.8°C 5 readings: 100.0, 100.1, 99.9, 100.0, 100.1°C 5 readings: 103.2, 103.1, 103.3, 103.2, 103.2°C 5 readings: 98.8, 101.4, 99.5, 100.6, 100.1°C 5 readings: 88.0, 112.0, 91.5, 109.0, 87.5°C

Accurate and precise

Precise but not accurate

Accurate but not precise

Neither accurate nor precise

Show What You Know

1. A balance that always reads 2 g too high gives very consistent readings. Is it accurate, precise, both, or neither? Explain the type of error affecting it.

Recall 2 marks

2. A student repeats an experiment 10 times to improve their results. Which type of error does this help reduce? Which type does it NOT fix? Explain why.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?