Grade 3Math
One Division on a Bar GraphRead graphs where one division is 2, 5, or 50, and choose the scale
One division on a bar graph is not always 1. With graphs where one division is 2, 5, 50, and so on, we learn how to find how much one division is and how to read the top of a bar. We also think about choosing the scale to fit the size of the numbers and the size of the paper.
The narration and the pictures are in Japanese. You can hear the same words that are used in class at a Japanese school.
- Video
- 1:27（6 scenes）
- Problems
- 3 problems
Open this lesson in Japanese（棒グラフの 1目もり）
Let's try
Write the math sentence in your notebook first, then open the answer.
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1This is a bar graph of favorite seasons. On the side scale, the space between 0 and 10 is split into 2 parts. The top of the summer bar is 1 division above 30. How many people is one division, and how many people chose summer?
Hint
First, count how many parts the space between two marks with numbers is split into.
Answer
10 ÷ 2 = 5, so one division is 5 people. For summer, 30 + 5 = 35, so it is 35 people.
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2On a bar graph, the space between 0 and 100 on the side scale is split into 5 parts. When the top of a bar is exactly halfway between the 120 mark and the next mark above it, what number do you read?
Hint
First, find how much one division is. Then check the numbers of the marks just below and just above the top of the bar.
Answer
It is 130. 100 ÷ 5 = 20, so one division is 20. The next mark above 120 is 120 + 20 = 140. It is halfway between 120 and 140, so you read 130.
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3You draw a bar graph on paper that has 10 divisions going up. The biggest number in the table is 90 people. Which fits on the paper: one division as 5 people, or one division as 10 people?
Hint
Multiply how much one division is by the number of divisions on the paper, and you will know the number at the top mark.
Answer
10 people. If one division is 10 people, 10 × 10 = 100, so you can draw up to 100 people. If it is 5 people, 5 × 10 = 50, so you can draw only up to 50 people, and the bar for 90 people goes off the paper.
Words in this lesson
- one division 1目もり
- The amount between two scale lines next to each other. On a bar graph, one division can be 2 people or 50 things.
- marks with numbers 数字の ある 目もり
- Marks with numbers written on them, like 0, 10, 20. The number of parts the space between them is split into tells you how much one division is.
- choosing the scale (the size of one division) 目もりを えらぶ
- Deciding how much one division should be, to fit the size of the numbers and the size of the paper.
For parents and guardians
- The names of lessons and the order of topics differ slightly between textbooks. This page follows the content of Japan's national curriculum guidelines (the Course of Study). The numbers in the tables were made up for this material and are not the results of a real survey.
- When reading a bar graph, the tip is to check "what one division stands for" before looking at the length of the bars. Count how many parts the space between two marks with numbers is split into, and divide the amount between them (10 or 100) by that number. It is the same way of thinking as reading the marks on a ruler or a number line.
- When you find a bar graph in a newspaper or a school newsletter, try checking together, "What does one division stand for?" Your child can notice that even with the same table, changing how much one division is changes the length of the bars, and that when the numbers are big, making one division bigger lets the graph fit on the paper.