🎯 WALT: We Are Learning To

• Read and interpret stem-and-leaf plots

• Calculate mode, median, range and mean from stem-and-leaf plots

• Compare data sets using measures of centre and spread

✅ Success Criteria - I can:

□ Identify the stem and leaf in a plot

□ Find the mode, median, range and mean

□ Compare two data sets

📖 Key Terms

Stem: The tens digit | Leaf: The units digit

Mode: Most common value | Median: Middle value when ordered

Range: Highest - Lowest | Mean: Sum ÷ Number of values

📊 Worked Example

Test scores for 12 students:

Key: 6|2 = 62 marks

5 | 8 9

6 | 2 5 7 7

7 | 1 3 8 8 9

8 | 4

Mode: 67 and 78 (both appear twice) | Median: 69.5 (average of 67 and 71)

Range: 84 - 58 = 26 | Mean: 828 ÷ 12 = 69

🏃‍♂️ Part 1: Reading Stem-and-Leaf Plots

Key: 17|5 = 175 cm

17 | 5 8 9

18 | 2 4 6 6 7

19 | 0 1 3

a) How many players are there? _______

b) What is the shortest height? _______ cm

c) What is the tallest height? _______ cm

a) Mode: _______ cm

b) Median: _______ cm

c) Range: _______ cm

d) Mean: _______ cm (show working below)

⚡ Part 2: Independent Practice

Key: 1|8 = 18°C

1 | 2 4 6 8 9

2 | 1 1 3 5 7 8 8 9

3 | 0 2

Calculate: Mode: _____ Median: _____ Range: _____ Mean: _____

Class A: Mean = 75, Range = 20

Class B: Mean = 73, Range = 35

a) Which class performed better on average? Explain.

b) Which class had more consistent results? Explain.

a) Calculate the mean with and without the outlier (95):

With outlier: _____ Without outlier: _____

b) Which measure (mean or median) is most affected by the outlier? Why?

🚪 Exit Ticket

In a stem-and-leaf plot showing ages, if the key is 3|2 = 32 years, what does 4|7 represent?

Reflection: What was the most challenging part of today's lesson?

📝 Differentiation Notes for Teachers

Support: Provide calculator, highlight key terms, work in pairs for Q3-4

Extension: Create own stem-and-leaf plot from given data, investigate interquartile range

Dyslexia-friendly: Use coloured overlays, read questions aloud, allow extra time