L1 · Mean, median, mode and range

Learning goal

“I can find the mean, median, mode and range of a data set - and I always put the values in order before I look for the middle.”

Mean — the value you get by sharing the total equally: add all the values, then divide by how many values there are.

Median — the middle value when the data is written in order. If there are two middle values, the median is halfway between them.

Mode — the value that appears most often. A data set can have one mode, or no mode.

Range — the spread of the data: the greatest value minus the least value.

Worked example

Jayden's goals in 5 soccer games: 2, 4, 3, 5, 6. Step 1: The mean answers the question "if the goals were shared equally among the games, how many per game?" Add the total: 2 + 4 + 3 + 5 + 6 = 20. Step 2: Share the total equally among the 5 games: 20 / 5 = 4. Step 3: Mean = 4 goals per game. The mean does not have to be one of the values - it is the equal share. Model both ways, side by side: five stacks of counters (2, 4, 3, 5, 6) levelled into five stacks of 4, AND the same values plotted on a number line with an arrow at 4 marked "balance point - the mean." Say it plainly: the mean uses EVERY value. Total first, then divide by the count.

Check yourself — explain it

To find the mean, why do we divide by 5?

Paired problem — example still visible

Pages read on 4 days: 12, 8, 10, 10 -> total 40, 40 / 4 = mean 10 pages

Faded completion — last step is yours

"Scores 3, 5, 7, 9: total = 24, and there are 4 values, so the mean is 24 / ___ = ___" -> 4, so the mean is 6

Ready to practise?

10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.

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