3
Bar graphs and pictographs
Discover Mathematics P2: Term 2, Lessons 101–110
GoalRead bar graphs and pictographs, including a pictograph where one picture stands for 2.
New words
bar graph · a graph that uses bars; the height shows the numberpictograph · a graph that uses pictureskey · tells what each picture stands formost / least · the biggest / the smallest number
Explanation
A bar graph shows numbers as bars. The taller the bar, the bigger the number. A pictograph shows numbers with pictures. Always read the key first. If the key says one picture is 2 flowers, then 3 pictures mean 3 groups of 2, so 2 + 2 + 2 = 6 flowers. To compare, find the most and the least, and subtract to see how many more.
Worked examples
In the fruit graph the tallest bar is watermelon: 10 children. The shortest bar is apple: 4 children.
How many more children chose watermelon than apple? Subtract: 10 − 4 = 6 more children.
In this pictograph each flower picture is 2 flowers. Sunday has 3 pictures: 2 + 2 + 2 = 6 flowers. Monday has 5 pictures: 10 flowers.
Class activity
Graph detectives. Look at a graph in a newspaper, a book or on a package. Ask the family: what does each bar or picture mean? What is the most? What is the least? Write one question about the graph and let someone answer it.
Practice
1
Which sport has the most children?
Football, with 9 children.
2
How many more children chose football than tennis?
9 − 4 = 5 more children.
3
How many children are in the graph in all?
9 + 7 + 4 + 6 = 26 children.
4
In the pictograph one balloon is 2 balloons. How many balloons does Hana have?
4 pictures: 2 + 2 + 2 + 2 = 8 balloons.
5
In the same pictograph, who has 6 balloons?
Nour: 3 pictures, 2 + 2 + 2 = 6.