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II.2 Interpret bar graphs

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What are bar graphs?

Bar graphs are visual displays that use bars to show and compare information. Each bar represents a category, and the height or length of the bar shows the value of that category.

Example:
  • A graph shows the number of books read by four students. The tallest bar means that student read the most books.
Note

Bar graphs help you understand information quickly by looking at patterns and comparing bar heights.

Understanding the parts of a bar graph

Every bar graph has important parts: a title, labels, a scale, categories, and bars. These parts work together to show what the graph is about and how to read the values.

Parts to Notice:
  • Title tells what the graph is showing.
  • Axis labels name the categories and values.
  • Scale shows the number each line or mark represents.
  • Bars show how much or how many for each category.
Note

The scale may skip-count by numbers like 2s, 5s, or 10s. Always check the scale before reading any bar.

How to read values on a bar graph

To read a bar graph, look at the top of each bar and match it to the value on the scale. This tells you the exact number for that category.

Example:
  • If a bar reaches the line between 20 and 30 on a scale that counts by 5s, the value is 25.
Note

Make sure you follow the scale carefully. A bar might not land exactly on a labeled number, so use the pattern of the scale to find the correct value.

Comparing information in bar graphs

Bar graphs make it easy to compare two or more categories. You can see which value is greater, smaller, or if two categories are equal.

Example:
  • If the bar for “Dogs” is taller than the bar for “Cats,” then more people chose dogs.
  • If two bars are the same height, the categories have the same value.
Note

Think about how much taller or shorter one bar is. This can help you find the difference between two values.

Interpreting multi-step problems with bar graphs

Sometimes bar graphs are used to solve multi-step word problems. You may need to add, subtract, or compare several pieces of information from the graph.

Example:
  • If one bar shows 18 students and another shows 25 students, you can subtract to find the difference: 25 − 18 = 7 students.
  • You may also add values from two bars to find a total amount.
Note

Always reread the question to understand what the problem is asking—difference, total, or comparison.

Reading double bar graphs

Double bar graphs compare two sets of related data. Each category has two bars shown side by side, each with its own color or pattern.

Example:
  • A graph shows how many minutes students spent reading in Week 1 and Week 2. Each category has two bars, allowing you to compare the weeks.
Note

Check the key or legend to understand what each color or pattern represents before interpreting the bars.