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Crowded planet: Earth is now home to a whopping 7 billion people. Here's what we know about them.

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Last fail, the world marked a major milestones According to the United Nations (UN), the number of people on Earth reached 7 billion--and counting.

It took from the dawn of humankind, some 50,000 years ago, until 1804 for the population to reach a billion. In 123 years it gained another billion--and yet another billion just 32 years later. Some people alive today have seen the population triple in their lifetimes!

What caused the population explosion? Medical advances like vaccines, along with better nutrition, and sanitation have helped more children survive to adulthood. People are also living longer than ever before.

"If there are more births than deaths, the population grows," says Gerhard Heilig, who compiles demographic information, or statistics about the characteristics of populations, for the UN.

More people means more strain on the environment. Luckily, human population growth has slowed in the past 50 years. Why?. "People, on average, are having fewer children than in the past," says Heilig. Despite that, numbers of people continue to rise. By the end of the century, the human population is projected to reach 10 billion.

As humanity grows, so do the challenges it faces. Many people still lack basic necessities, such as clean water and food. There also aren't enough jobs or schools for everyone. Tackling these problems is important for everyone's future as Earth becomes increasingly cramped.

WHO ARE THE 7 BILLION?

If 100 people were chosen to represent the diversity of humans on the planet, they would have the following demographics. (These numbers translate into percentages that can be applied to the entire population.)

GENDER

51 men, 49 women

RELIGION

33 Christian, 22 Muslim, 14 Hindu, 7 Buddhist, 12 other, 12 non-religious

NATIVE LANGUAGE

12 Mandarin Chinese, 5 English, 5 Spanish, 3 Arabic, 3 Hindi, 72 other

AGE

27 are younger than 15, 65 are between ages 15 and 65, 8 are older than 65

EDUCATION

16 can't read or write, 35 have Internet access

LOCALE

51 live in cities, 49 live in rural areas

YOUR ECOLOGICAL FOOTPRINT

The average American's ecological footprint (measure of a person's impact on the environment) is nine times larger than that of a person in a developing country. If everyone consumed as many resources as Americans do, we'd need four more Earths to support us all.

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WHERE
DO THE 7
BILLION LIVE?

Two out of every
five people in the world
currently live in China or
India. But from now until
the end of the century, the
largest growth in the population
is predicted to come
from Africa--not Asia.
"Africa alone will gain
another 2.5 billion
people by 2100,"
predicts Gerhard
Heilig of the
UN.

OCEANIA 0.5%

SOUTH 5.7%
AMERICA

NORTH 7.9%
AMERICA

EUROPE 10.7%

AFRICA 14.8%

ASIA 60.4%

Note: Table made from pie chart.


FAMILY SIZE

Worldwide fertility rates have fallen to the current global average of 2.6 children per woman. Areas with higher fertility rates have a growing, younger population, while areas with lower fertility rates are experiencing a shrinking, aging population.

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AFRICA

4.6 children per woman

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NORTH AMERICA

2 children per woman

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ASIA

2.3 children per woman

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EUROPE

1.5 children per woman

POPULATION BOON

This graph shows past and future billion-person milestones, When is the world's population growth predicted to almost level off?

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STANDARDS

NATIONAL SCIENCE EDUCATION STANDARDS:

Grades 5-8: Populations, resources, and environments

Grades 9-12: Population growth

COMMON CORE STATE STANDARD:

LITERACY IN SCIENCE: 7. Integrate quantitative information expressed in words and visually (graph, table, etc.).

OBJECTIVE

Understand the causes and effects of Earth's human population reaching 7 billion.

BEFORE READING

* How many people live on Earth? In the U.S.? In your state and town? (7 billion; 313 million; Answers will vary.)

* What factors affect the size of a population? (number of births, how long people live, etc.)

* What happens when Earth's population grows? (Areas become more crowded. More water, food, energy, and other resources are needed.)

LESSON

1. Ask students the first prereading question. Ask them if they think Earth's population is growing, staying the same, or decreasing. Ask the remaining questions and discuss what factors students think contribute to changes in populations.

2. Go to www.scholastic.com/scienceworld. Open up the digital edition to page 12 and have students do the same in their magazines. Call on a student to read the headline and the text just below it. Read the main text of the article together, calling on student volunteers at the end of each paragraph.

3. Observe the various charts and graphs in the article. Ask students why they think the editors chose to display the information in this manner.

4. Turn to page 13 and zoom in on the "Population Boom" graph. Have students look at the graph to determine approximately what the world population was when they were born. How much will the population grow in the students' lifetimes? Engage the class in a discussion about why the population has boomed in the past 50 years. Ask students if they think there is a limit to how large the population can grow.

5. Pass out the "Around the World" skills sheet from the online database at www.scholastic.com/scienceworld. Leave the digital edition up on the screen, and zoom into the various graphs as students further analyze the information found in each graph.

DISCUSSION

Enlarge and read the text in the box labeled "What Do You Think?" on page 12: "What are some ways to address the issues facing humanity as our population increases?" To limit population growth, China has placed restrictions on the number of children a couple can have. Do students think this is a good idea? Why or why not?

ASSESSMENT

After class, go over students' responses to the "Around the World" work sheet. Did they identify the appropriate information for each graph?

DON'T TEACH BIOLOGY?

Go to www.scholastic.com/scienceworld to download these assessment skills sheets instead:

EARTH SCIENCE: TRACKING TEENS

A booming population puts a strain on the planet's resources. Read this passage to learn about a group of teens who used cell phones to find out about their impact on the environment by tracking their own carbon-dioxide emissions.

PHYSICS: ENERGY BOOM

More people on the planet means that more energy is consumed for things like powering lights and generating heat. Use this graphing activity to compare the populations and energy consumption of various countries.

RESOURCES

* VIDEO EXTRA: Watch a video about the world's growing population at: www.scholastic.com/scienceworld.

* Check out the world population clock at: www.worldometers.info/world-population.

* Find more teacher resources, including printable work sheets, about the world's population growth at: www.worldof7billion.org/teacher_resources.
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Title Annotation:BIOLOGY: POPULATION
Author:Crane, Cody
Publication:Science World
Geographic Code:1USA
Date:Feb 13, 2012
Words:1132
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