World History, Grades 9-12

3.6 Interpreting Graphs

GRAPHS show statistical information in a visual manner. Historians use graphs to

show comparative amounts, ratios, economic trends, and changes over time.

LINE GRAPHS can show changes over time, or trends. Usually, the horizontal axis

shows a unit of time, such as years, and the vertical axis shows quantities.

PIE GRAPHS are useful for showing relative proportions. The circle represents the

whole, such as the entire population, and the slices represent the different groups that

make up the whole.

BAR GRAPHS compare numbers or sets of numbers. The length of each bar indicates a

quantity. With bar graphs, it is easy to see at a glance how different categories compare.

Understanding the Skill

STRATEGY: STUDY ALL THE ELEMENTS OF THE GRAPH. The line graphs below show

average global temperatures and world population figures over a period of 25,000 years.

Pose questions about geographic patterns and distributions shown on this graph; for

example, when did worldwide temperature start to rise?

STRATEGY: WRITE A SUMMARY.

Use the answers to your questions about geographic patterns and distributions to

write your summary paragraph.

Applying the Skill

WRITE YOUR OWN SUMMARY. Turn to Chapter 31, page 908, and look at the graph

“World Trade, 1929–1933.” Study the graph and write a paragraph in which you

summarize what you learn from it.

Section 3: Exploring Evidence: Print, Visual, Technology Sources

Read the title to identify the main

idea of the graph. When two subjects

are shown, look for a relationship between

them. This set of graphs shows that the

agricultural revolution had links to both

global temperature and population.

Read the vertical axis. The temperature

graph shows degrees Fahrenheit. The other

shows population in millions, so that 125

indicates 125,000,000.

Note any information that is high-

lighted in a box.

Read the horizontal axis. Both graphs

cover a period of time from 25,000 years

ago to 0 (today).

Look at the legend to understand

what colors and certain marks stand for.

Summarize the information shown in

each part of the graph. What trends or

changes are shown in each line graph?

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4

3

2

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R28SKILLBUILDERHANDBOOK

Write a paragraph to summa-

rize what you learned from

the graphs.

Agricultural Revolution

50 °

52 °

54 °

56 °

58 °

60 °

2025 1015 05

Average Global Temperature

(in Fahrenheit)

Years Ago (in thousands)

beginnings of

agriculture

last ice age

Temperature

0

25

50

75

10 0

125

150

2025 1015 05

Years Ago (in thousands)

Hunting-

gathering

stage

Agricultural

Revolution

World Population

(in millions)

Post-

Agricultural

Revolution

Population

1

2

3

4

5