Read bar graphs

What you will learn

• Read bar graphs

Models used: number sentences, stories, diagrams.

Before you start

• Read tables

Read the scale, then the bar

Each step up the scale stands for 2 votes.

1. Each step up the scale stands for 2 votes.

   On a scale of 5, a bar of seven blocks shows 35.

2. The mango bar reaches 6. That means 6 votes, not 3 votes.

   3 × 2 = 6

3. Both bars use the same scale. Compare their lengths and read the names beside them.

   The apple bar reaches 4. Compare the tops: mango has 2 more votes.

   6 − 4 = 2

   Mango6

   Apple4

   Difference: 2

Worked example: A new example, together

What is the difference between the greatest and least counts?

1. Find what one step on the axis is worth, then read the top of the bar.

   Labels and scales determine the numerical value represented by each category.

2. Each marked interval represents 10.

   What is the difference between the greatest and least counts?

   20

3. Each marked interval represents 10.

4. Subtract the smaller requested value from the larger.

5. The answer is 20.

6. Check the result against the question we started with.

   Adding the size of the change to the smaller count gives the larger count.

   We found 20. Labels and scales determine the numerical value represented by each category.

Common mistakes to discuss

• Reading the bar as its count. Read the height against the scale. On a scale of 5, a bar of seven blocks shows 35.

Check your understanding

• Read bar graphs
• read a bar graph using its scale
• check the answer against the original quantities and units

Explain your reasoning to an adult, then try a fresh question in the interactive lesson. A result from one attempt is not proof of lasting mastery.