Introduction to Data Handling
Primary 4 · Mathematics
Introduction to Data Handling
Lesson 2 of 5
25 min
Let's begin
Byiringiro sits by the road outside his school at break. "I think more motos pass here than anything else," he says. Keza is not sure. "Let's not guess," she says. "Let's count."
Good data starts with a clear question and a careful way of collecting the answers.
Byiringiro's question is: "Which kind of vehicle passes our school most often?" Now he needs a way to collect the data.
When you count things quickly, draw one small stroke for each one. This is a tally mark. Draw four strokes, then draw the fifth stroke across them to make a bundle of 5. Bundles make counting fast: count in fives, then add the single strokes.
The moto row has 2 bundles and 3 single strokes: 5 + 5 + 3 = 13 motos. Byiringiro was right, but now he has proof!
Tip
Count in fives. Four strokes and one across make a bundle of five: 5, 10, 15 … then add the single strokes at the end.
Work each one in your exercise book first. Then tap Show answer to check.
A tally has 3 bundles of five and 1 single stroke. What number is that?
Answer: 16, because 5 + 5 + 5 + 1 = 16.
How would you show 7 with tally marks?
Answer: One bundle of five and 2 single strokes.
You want to know the heights of pupils in your class. Which way of collecting data will you use?
Answer: Measuring.
You want to know how much rain fell each day last month. Where could you find the data?
Answer: In records, such as the rainfall written down each day at a weather station.
Why is it better to count the vehicles than to guess?
Answer: Counting gives real data we can trust. A guess can be wrong.
What you learned today
Sources and credits
The tally marks section and the vehicle-counting example were written by Ganzaa. The stories, Rwandan examples, diagrams and practice questions were written by Ganzaa.
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