Learning intention
Students learn to describe numerical data using mean, median, mode and range, and recognise that different measures can give different impressions of the same data.
Chapter 8D within the eight-lesson Year 8F Statistics sequence at Wallan Secondary College, developing mean, median, mode and range and justifying which measure best represents a data set. The original plan was labelled Lesson 4 before an 8A/8B consolidation lesson was added.
Status: 8D teaching has taken place. The exact date and final student achievement judgements must be confirmed from the placement records, not inferred from the preparation of these resources.
Students learn to describe numerical data using mean, median, mode and range, and recognise that different measures can give different impressions of the same data.
Students calculate the mean, identify median and mode, calculate range, and explain which measure is most useful for describing a data set.
Compare Team A scores 4, 5, 5, 6, 10 with Team B scores 5, 6, 6, 6, 7. Students discuss which team did better and what single number could describe the centre of each group.
Model 3, 5, 5, 7, 10 one measure at a time: mean = 6, median = 5, mode = 5 and range = 7.
Use 4, 6, 7, 7, 8, 10. Students calculate each measure with teacher prompting and explicitly practise an even-number median.
Use 2, 4, 6, 8, 10, 12 to reinforce that an even-sized data set has two middle values and therefore median = (6 + 8) ÷ 2 = 7.
Compare weekly earnings of $200, $220, $230, $240 and $1500. The mean is $478 while the median is $230, illustrating how an extreme value can pull the mean away from a typical value.
Students calculate mean, median, mode and range for 6, 8, 8, 9, 11, 12, 16 and justify which measure best represents the centre before moving to selected Chapter 8D textbook questions.
Live questioning, calculation checks, observation of whether data are ordered for the median, accuracy of mean and range, justification of the best measure, and targeted monitoring of the five focus students.
Worked-example chunking, prominent data values, visual highlighting of middle/extreme values, formula reminders, wait time and targeted prompts support access. Extension asks students to compare how mean and median respond to an extreme value.
Students independently find the median, mode, range and mean. Expected responses are median = 4, mode = 4, range = 6 and mean = 5. The bonus prompt asks what changes most if 9 becomes 50 and why.
Next evidence: after teaching, the reflection and mentor-feedback section will record misconceptions, focus-student evidence and any change required before Lesson 5.
Open 8D · Range and Measures of Centre in Gamma →
Textbook: Essential Mathematics for the Victorian Curriculum, Year 8, Chapter 8D, pp. 569–575.