Learning Intentions

• Collect and record simple data from class surveys or local contexts (e.g., rainfall, favourite fruits, number of goats).
• Represent data using tally charts, frequency tables, pictograms, bar graphs and simple pie charts.
• Calculate and interpret mean (average), median, mode and range for small datasets.
• Understand basic probability language: experiment, outcome, event; and compute simple probabilities (fraction or percentage).

Key Terms

Collecting and Recording Data

Start with a question that can be answered by counting or measuring. Examples relevant to Kenya and a class of age_replace:

• Survey: "Which fruit is your favourite?" — mango, banana, avocado, orange.
• Measure: Daily rainfall (mm) for a week in Kisumu or Mombasa.
• Count: Number of passengers boarding different matatu routes in a day (colours of matatu).

Recording with a Tally Chart

Representing Data

Use clear displays so others can understand results quickly.

Pictogram (1 picture = 1 pupil)

Example: Favourite sport in class (football ⚽, netball 🏐, running 🏃)

Bar Chart (simple SVG)

Label axes and give units (e.g., number of pupils, mm of rainfall).

Summary Measures (Mean, Median, Mode, Range)

• Mode: The value that appears most often. Example: marks {56, 60, 60, 72} → mode = 60.
• Median: Middle value after sorting. For even number of items, take the average of two middle values. Example: {50, 54, 60, 68} → median = (54 + 60)/2 = 57.
• Mean (Average): Add all values then divide by the number of values. Example: marks {50, 54, 60} → mean = (50 + 54 + 60) / 3 = 164/3 ≈ 54.67.
• Range: Difference between largest and smallest. Example: {20, 30, 45, 60} → range = 60 − 20 = 40.

Class tip: Use real school data (heights, scores) to practise calculating these statistics.

Basic Probability

Probability measures how likely an event is to happen. It can be shown as a fraction, decimal or percentage.

Probability formula: P(event) = Number of favourable outcomes / Total number of possible outcomes

Common simple examples

• Coin toss — P(heads) = 1/2 = 0.5 = 50%.
• Die roll — P(4) = 1/6 ≈ 0.167 ≈ 16.7%.
• Class example with Kenyan context: A matatu park has 10 matatus: 4 green, 3 white, 3 red. Probability of picking a green matatu = 4/10 = 0.4 = 40%.

Simple events and language

Certain event: probability = 1. Impossible event: probability = 0. Likely/unlikely are informal ways to describe comparison of probabilities.

Worked Examples

Simple Classroom Activities (for age_replace)

• Survey classmates on favourite drink (tea, milk, juice). Record tallies and make a pictogram.
• Measure shoe sizes and make a frequency table; compute median and mode.
• Probability game: Put 10 coloured beads in a bag (3 red, 4 blue, 3 yellow). Pupils predict and test the probability of drawing a blue bead.
• Collect weekly rainfall (mm) for your local area and plot a simple line or bar chart to show changes.

Practice Questions

1. A class of 20 pupils: 6 like mango, 8 like banana, 4 like avocado and 2 like orange. Make a frequency table and draw a pictogram (1 pict = 2 pupils). What is the probability that a randomly chosen pupil likes banana?
2. Find the mean, median, mode and range for the set: {12, 15, 15, 18, 21}.
3. A spinner has 4 equal sections coloured: red, blue, green, yellow. What is P(not green)?

Tips & Common Mistakes

• Always label charts and include units (e.g., "Number of pupils", "mm").
• When computing the mean, check you divided by the correct number of items.
• For probability, ensure the total number includes all possible outcomes.
• Use real local examples (market prices, rainfall, matatu colours) to make lessons relevant to Kenyan learners.