Evaluating the range
I can evaluate the range as a measure of spread, including a consideration of outliers.
Evaluating the range
I can evaluate the range as a measure of spread, including a consideration of outliers.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- The range can be affected by outliers in the data.
- Removing these outliers will change the value of the range.
- Outliers must be carefully considered and only removed if they were recorded in error.
Keywords
Outlier - A data point that is extremely large or small compared to the rest of the dataset.
Range - A measure of spread. It is found by finding the difference between the highest and lowest values.
Spread/dispersion - Describes how far apart pieces of data in a dataset are.
Common misconception
"Adding or removing a data point from a dataset will always change the value of the range"
The range only changes if: the data point added becomes a new max or min value, or the data point removed is the current max or min value.
To help you plan your year 8 maths lesson on: Evaluating the range, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 8 maths lesson on: Evaluating the range, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 3 maths lessons from the Numerical summaries of data unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
Licence
Starter quiz
6 Questions
The largest value is -
10
The smallest value is -
1
Calculation to find range -
10 − 1
The range is -
9
Number not used to find range -
4
1, 3, 7, 8, 10 -
9
3, 1, 10, 10, 12 -
11
3, 9, 11, 15, 14 -
12
4, 9, 8, 7, 7, 14, 12, 13 -
10





Exit quiz
6 Questions



The outlier -
23
The range with the outlier -
24
The range without the outlier -
11
The largest data point -
47

Definitely keep -
An outlier of 28 for number of days in a month without rain.
Definitely remove -
A student walked 200 km to the supermarket.
Investigate further -
19 cats had a mass of 4 - 6 kg. Outlier had a mass of 11 kg.