Discover Mathematics P4: Term 2, Unit 11, Lessons 1–5
GoalPlan a class survey, collect the answers with tally marks, and show the results in a graph.
New words
survey · asking a question to many people to collect datatally marks · small lines we draw while counting; every fifth line crosses the four before itcategory · one of the groups the answers are sorted into
Explanation
A survey collects data. First choose a clear question with a few possible answers, for example: How do you get to school? (walk, microbus, car, bus, bicycle). Then ask everyone once and record each answer with a tally mark. Count the tally marks and write the numbers in a table. Check that the numbers add up to the number of children you asked. Next choose a scale so that the longest bar fits on your page, draw the bars with equal width, and write a title and the names of the categories. Last, answer questions with the graph: which is the most common, how many more, how many in all. A good question is neutral. It does not push people to one answer.
Ask a clear question→Tally the answers→Count and make a table→Choose a scale and draw bars→Read the graph
Worked examples
Way to school
Walk
Microbus
Car
Bus
Bicycle
Children
11
9
6
3
1
Class 4C asked 30 children how they get to school. The table shows walk 11, microbus 9, car 6, bus 3 and bicycle 1. Check the total: 11 + 9 + 6 + 3 + 1 = 30, the number of children asked. It matches.
Draw the data as a bar graph with one block for each child. Which way is the most common? Walking, with 11 children. How many more children walk than come by car? 11 − 6 = 5 children. How many come by microbus or bus? 9 + 3 = 12 children.
The class also asked boys and girls separately about their break snack. Fruit: boys 6, girls 7. Sandwich: boys 8, girls 5. Juice: boys 3, girls 4. Two sets of data need a double bar graph. Boys asked: 6 + 8 + 3 = 17. Girls asked: 7 + 5 + 4 = 16. Together 17 + 16 = 33 children.
Class activity
Make your own survey. Choose a question for your class or family, such as: Which sport do you like best? List 3 or 4 answers. Ask at least 20 people, make tally marks, count them and draw a bar graph. Write one sentence that tells what your graph shows.
Practice
1
A survey of balloons shows red 8, blue 6, green 4 and yellow 2. How many balloons are there in all?
8 + 6 + 4 + 2 = 20 balloons.
2
The values are 20, 40 and 60. Which scale lets the longest bar fit on a page: 1 block = 1, or 1 block = 10? How many blocks long is each bar with your scale?
1 block = 10. The bars are 2, 4 and 6 blocks long.
3
Seven children walk to school. The scale is 1 block = 1 child. How long is the bar?
7 blocks.
4
Which graph shows how many boys and how many girls chose each subject: single or double?
A double bar graph.
5
Karim asks: “Don’t you agree that football is the best sport?” What is wrong with this question? Write a better one.
It pushes people to say yes. A neutral question is: Which sport do you like best: football, swimming or running?
