2
A pictograph from a story
Discover Mathematics P2: Term 2, Lessons 111–120
GoalTurn a story into a pictograph by choosing a key and counting by twos.
New words
key · tells how many each picture stands forpictograph · a graph made with picturescount by twos · say 2, 4, 6, 8, 10
Explanation
A story can become a pictograph. Read: in the school garden Youssef picked 8 flowers, Salma 6, Karim 4 and Mina 10. The numbers are big, so we choose the key one picture = 2 flowers. Youssef: count by twos to 8: 2, 4, 6, 8 is 4 pictures. Salma needs 3 pictures, Karim 2 and Mina 5. Write a title and the key under the graph.
Worked examples
How many pictures for 8 flowers? Count by twos on the number line: 4 jumps of 2 reach 8, so Youssef has 4 pictures.
The same story as a bar graph. The bar for Mina is 10 tall, and her row in the pictograph has 5 pictures: 5 pictures of 2 is 10.
When is the key = 2 good? When the numbers are even, like 8, 6, 4 and 10. For 7 you could not make an exact count by twos, so use a key of 1.
Class activity
Story graph. Make up a story with three or four friends who collect things: shells, stones or stickers, with even numbers up to 10. Choose one picture to draw. Write the key one picture = 2. Draw the pictures in rows and ask someone to read the totals.
Practice
1
Hana ate 6 dates, Omar ate 10 and Nour ate 4. The key is one picture = 2 dates. How many pictures for each child?
Hana 3, Omar 5, Nour 2.
2
In the pictograph one balloon is 2 balloons. How many balloons does Karim have?
2 pictures: 2 + 2 = 4 balloons.
3
With the key one picture = 2, how many pictures show 12?
6 pictures, because 2 + 2 + 2 + 2 + 2 + 2 = 12.
4
Why is the key one picture = 2 not good for 7 books?
Counting by twos goes 6, 8 and skips 7. Use a key of 1 instead.
5
Show 6 stickers and 4 stickers in a pictograph with the key one picture = 2. How many pictures in each row?
3 pictures and 2 pictures.