Working Scientifically and Required Practicals
The skills every scientist needs: variables and fair tests, accuracy and precision, reducing error with repeats and a mean, spotting anomalies, and drawing conclusions from data.
Get the method right under pressure
Free interactive practice on the steps that lose marks under exam pressure.
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Thinking like a scientist
Every science experiment relies on the same set of skills. A scientist changes one thing, measures another, keeps everything else the same, and repeats the readings to be sure. This module teaches these working-scientifically skills, which are tested even when the practical itself is done in the lab.
Variable and hypothesis terms
Learn these four terms before you plan an investigation.
Accurate or precise?
Accuracy and precision sound similar but mean different things.
Say why the step helps
Explain why a step helps, not just what it is. Repeating the readings and taking a mean reduces the effect of random error, so the result is more reliable. Spotting an anomalous result and leaving it out of the mean stops one odd reading from spoiling the conclusion.
Match the variable
- independent variable
- dependent variable
- control variable
- hypothesis
- the one thing you deliberately change
- the thing you measure each time
- anything you keep the same to be fair
- a prediction you can test
Match the term
- fair test
- accuracy
- precision
- anomalous result
- an investigation where only one variable is changed
- how close a measurement is to the true value
- how close repeated measurements are to each other
- a result that does not fit the pattern
What is a fair test?
What is a fair test?
- An investigation where you change only one variable and keep the rest the same.
- An investigation where you change several variables at once.
- An investigation with no measurements.
- An investigation that is repeated several times.
More reliable results
Select the TWO things that make results more reliable.
- Repeating the readings.
- Taking a mean of the readings.
- Measuring only once.
- Guessing the values.
Order the investigation
Put the steps of an investigation in order, earliest first.
- Make a hypothesis
- Plan a fair test
- Take repeat readings and record them
- Draw a conclusion from the results
Summarise the skills
In an investigation the _____ variable is the one you change, and the _____ variable is the one you measure. To keep it a fair test you keep the other, or _____, variables the same. A result that does not fit the pattern is called an _____ result. Repeating readings and taking a _____ makes the results more reliable.
Find the mean
Three readings are 4, 5 and 6. What is the mean of these three readings?
Find the reliability boosters
Tap the TWO things that improve reliability.
- Repeating the readings
- Changing several variables at once
- Taking a mean of the results
- Measuring only one time
- Guessing the result
Which variable?
A student investigates how the temperature of water affects how fast sugar dissolves. Decide which variable each one is.
- The temperature of the water, which the student changes
- The time taken for the sugar to dissolve, which the student measures
- The amount of sugar, which is kept the same each time
Plan a fair test
A student wants to find out how the temperature of water affects how fast sugar dissolves. Describe how they could plan a fair test to investigate this.
- Name the independent and dependent variables
- Name one control variable
- Explain how repeating readings makes the results more reliable