Lubricants are substances added between two surfaces to reduce the friction between them.
In a fair test, only the variable we are testing is changed.
In a fair test, everything we are not testing is kept the same for every measurement.
Repeat measurements help check for anomalous results.
A mean combines repeat measurements into a single result.

Common misconception

Friction is only between solids that are rubbing together.

Highlight the different amounts of friction between the solids that are separated by different liquids.

Keywords

Lubricant - Lubricants are substances added between two surfaces to reduce the friction between them.
Fair test - In a fair test, only the variable being tested is changed, so any differences in results can only be due to that variable.
Anomalous result - Anomalous results are ones that do not fit the pattern we see for other measurements.
Repeat measurement - A repeat measurement is when you make a measurement again to check the result.
Mean - A mean combines repeat measurements into a single result.

The task in learning cycle 2 involves pupils calculating mean results for sample data, this allows easier assessment of understanding of all students. Teachers might consider whether students could calculate means for their own collected data too.

Teacher tip

Content guidance

Equipment requiring safe usage.

Supervision

Adult supervision recommended.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Worksheet

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Starter quiz

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6 Questions

Q1.

An object is set sliding across a surface. The greater the friction, the the distance the object will slide, before it stops.

Correct Answer: shorter, lower, less, smaller, less far

Q2.

For an experiment to be a fair test, how many things can be changed between each test?

For a fair test, nothing can be changed between each test.

Correct answer: For a fair test, only one thing can be changed between each test.

For a fair test, only two things can be changed between each test.

Q3.

How do scientists check for mistakes in their results during the experiment?

They always have another scientist watching the experiment too.

Correct answer: They do repeat measurements.

They set up their equipment really carefully.

Q4.

A scientist slides a mass across a desk four times, in the same way each time. The distances travelled by the mass each time were 34, 37, 55 and 35 cm. Which result is probably a mistake?

34 cm

37 cm

Correct answer: 55 cm

35 cm

Q5.

Which of the following statements are examples of lubricants (substances added to reduce friction)?

Correct answer: Oil on a bike chain

Correct answer: Grease in an engine

Correct answer: Water in a water slide

Paint on wooden floorboards

Q6.

A scientist slides a mass across a desk four times, in the same way each time. The distances travelled by the mass each time were 54, 57, 54, and 55 cm. What should be used as the final result?

The lowest result (54 cm).

The highest result (57 cm).

The most common result (54 cm).

Correct answer: The mean (average) result (55 cm).

Exit quiz

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6 Questions

Q1.

A lubricant is a substance added to a surface to reduce the ...

Correct Answer: friction, friction force, frictional force, grip, friction forces

Q2.

What is an anomalous result?

A result that just feels wrong.

Correct answer: A result that doesn't fit with other results.

A result that is very similar to other results.

Q3.

A scientist slides a mass across a desk three times, in the same way each time. The distances travelled by the mass were 20, 24 and 25 cm. Calculate the mean result. Mean result = cm.

Correct Answer: 23, twenty three

Q4.

A scientist slides a mass across a desk four times, in the same way each time, to check for mistakes. The distances travelled by the mass were 22, 19, 23, and 46 cm. Which result is anomalous?

22 cm

19 cm

23 cm

Correct answer: 46 cm

Q5.

Which is the correct reason why, in a fair test, the only thing we change is the variable we are testing, and everything we are not testing has to be kept the same?

So we can do repeat results.

So we can identify anomalous results.

Correct answer: So we can be sure that different results are caused by the one thing we changed.

Q6.

A scientist slides a mass across a desk four times, in the same way each time. The distances travelled by the mass were 70, 73, 34 and 69 cm. Calculate the mean result. Mean result = cm.

Correct Answer: 71, 70.6, seventy one

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