This mini-lesson walks you through the whole KS3 Statistics strand: the three averages (mean, median, mode) and the range; how to read and draw bar charts, pie charts, pictograms and frequency tables; and how scatter graphs show correlation between two things.
Work through each screen, answer the questions as you go (some are wordy, some are calculations) and collect ⭐ stars. Press Start when you're ready.
An average is one number that stands in for a whole set of data — a "typical" value. There are three you must know, plus a measure of spread:
Memory hook: mode = most; median = middle; the range is not an average — it tells you how spread out the data is.
Five test scores: 6, 8, 5, 9, 7.
Sum = 6 + 8 + 5 + 9 + 7 = 35
Mean = 35 ÷ 5 = 7
Watch out: a single very big or very small value (an outlier) can drag the mean away from what's typical — that's when the median is often a better choice.
For the median, always put the data in order first, then find the middle. For the mode, just spot the most common value.
Data: 12, 7, 9, 3, 10. In order: 3, 7, 9, 10, 12.
The middle value is 9, so the median = 9.
Shoe sizes: 5, 6, 6, 7, 6, 8. The value 6 appears three times.
Mode = 6.
Even number of values? The median is the mean of the middle two. For 4, 6, 9, 11 the middle two are 6 and 9, so median = (6 + 9) ÷ 2 = 7.5.
The range is not an average — it tells you how spread out the data is. A small range means the values are close together; a large range means they are widely scattered.
Temperatures: 18, 21, 15, 24, 19 °C.
Range = 24 − 15 = 9 °C
Comparing two sets: use an average to compare what's typical and the range to compare how consistent they are. A player with the same mean but a smaller range is more reliable.
Both are "averages", but they behave differently when the data has an outlier — one value much larger or smaller than the rest.
Wages (£1000s): 18, 19, 20, 21, 150 (the boss).
Mean = 228 ÷ 5 = 45.6 → but nobody earns near that!
Median = 20 → a much more typical figure.
Common mistake: people say "the mean is always the best average". Not true. Use the median when there is an outlier, because the mean gets dragged towards it. Use the mode for non-numerical data like favourite colour.
Tap an average on the left, then tap the situation on the right that it suits best.
A frequency table records how many times each value occurs. It's a tidy way to handle lots of repeated data.
Mode from a table: the mode is the value with the highest frequency, here 1 goal (frequency 6). The total frequency (3 + 6 + 4 = 13) is how many pieces of data there are.
A bar chart shows data in separate categories using bars of equal width. The height of each bar shows its frequency. Bars have gaps between them.
Always check the axes. The gaps between bars show the categories are separate. Read the height off the vertical (frequency) axis carefully — note what each gridline is worth.
A pictogram uses a symbol to stand for a number of items. You must read the key — each symbol can be worth more than one.
Common mistake: counting the symbols instead of the value. Always multiply the number of symbols by what the key says one symbol is worth.
A pie chart shows how a whole is shared out. Each slice is a fraction of the whole circle, and the whole circle is 360°.
Common mistake: a pie chart shows proportion, not amount. Two pie charts can have identically sized slices while representing totally different totals. And every slice is a share of 360° — the angles must add to 360°.
Tap the chart type that best matches each job.
A scatter graph plots two variables against each other (this is called bivariate data) to see if they are linked. The pattern of points shows the correlation:
A scatter graph can show two things rise together — but that does not prove one causes the other. There may be a hidden third factor.
Ice-cream sales and drowning incidents both rise together over the year.
Ice cream doesn't cause drowning! The hidden factor is hot weather, which raises both.
Common mistake: writing "X causes Y" from a scatter graph. You can only say they are correlated (linked). Proving cause needs a fair, controlled experiment.
Mean: sum of values ÷ number of values
Median: order the data, take the middle value
Mode: the most common value
Range: largest − smallest (spread, not an average)
Pie chart: slice angle = (category ÷ total) × 360°
Scatter graph: positive / negative / no correlation — but correlation ≠ causation
You've covered the whole KS3 Statistics strand — averages and spread, tables and charts, and bivariate data. Press Finish to see your score.
You've worked through Statistics for KS3 Mathematics. 🎉
Your stars: 0 / 0
Next: test yourself in the Evaluate stage Confidence Quiz, then lock it in with Verify.