Lessons 38: Interpreting Graphs

New Concept

Graphs use pictures, bars, lines, or circles to visually represent numerical data, helping us understand and compare information.

Quantitative information is data in the form of numbers. It tells us an amount of something.

What’s next

This is your foundation for data literacy. Next, you'll walk through worked examples on how to interpret pictographs, bar graphs, line graphs, and circle graphs to answer specific questions.

Property

A pictograph uses pictures to represent a quantity of data. A key shows the value that each picture represents.

Examples

• If one tire symbol = 100 tires, then $5\frac{1}{2}$ symbols represent $5 \times 100 + 50 = 550$ tires.
• If a book icon = 20 books, then 4 icons mean $4 \times 20 = 80$ books were read.

Explanation

This graph uses pictures instead of bars. The key is your decoder ring—it tells you what each picture is worth. Just count the pictures and multiply to find the total amount. It makes large numbers easy to see!

Property

A bar graph uses the lengths of solid bars to represent and compare quantitative information. A scale along one axis shows the value corresponding to the bar's length.

Examples

• If the bar for Room 14 reaches the 8000 line, that class collected 8000 cans.
• If Room A's bar is at 3000 and Room B's is at 9000, Room B collected three times as many cans.

Explanation

A bar graph is like a race where the bars show the results. Taller bars mean bigger numbers! Just check the bar's height against the scale on the side to find its value and easily compare it with the others.

Property

A line graph uses points connected by lines to show how a value changes over time. An upward slope means an increase; a downward slope means a decrease.

Examples

• To find Paul's score for Game 3, find '3' on the bottom axis and trace up to the point, which lines up with 175 on the side axis.
• Since the line generally moves upward, Paul's scores were improving over the six games.

Explanation

A line graph tells a data story over time. Follow the line to see the ups and downs! An upward climb means growth, while a downward slide means a decrease. It’s perfect for spotting trends.