Name
Date
Class
Early Earth
Inquiry Warm-Up, How Could Planet Earth Form in Space?
In the Inquiry Warm-Up, you investigated how to make a model of early Earth. Using
what you learned from that activity, answer the questions below.
1. OBSERVE What happened to the iron filings after blowing through
the straw in Step 4?
2. DRAW CONCLUSIONS Why did you get this result from blowing through
the straw?
3. APPLY CONCEPTS How does the magnet in the activity work like Earth’s
gravity?
4. MAKE GENERALIZATIONS Do you think other planets may have formed
as Earth did? Explain.
127A
Name
Date
Class
Early Earth
How Did Earth Form?
1a. IDENTIFY Earth formed
years ago.
b. SEQUENCE Write the numbers 1, 2, and 3 to show the correct order of
the events below.
Ozone layer forms.
Earth loses its first atmosphere.
Volcanoes and collisions with comets add water vapor to the atmosphere.
c.
CHALLENGE How would Earth’s atmosphere be different if organisms
capable of photosynthesis had not evolved.
I get it! Now I know that key features of early Earth were
I need extra help with
127B
Name
Date
Class
Early Earth
On a separate sheet of paper, explain what scientists have theorized about important
events involving early Earth.
127C
Name
Date
Class
Early Earth
Understanding Main Ideas
Put the six events or processes in the correct sequence by writing their letters in the
correct order in the numbered blanks below.
A. Volcanic eruptions release carbon dioxide into the atmosphere.
B. Early organisms release oxygen into the air.
C. Oceans form on Earth’s surface.
D. Hydrogen and helium are captured by gravity to form an atmosphere.
E. A dense, iron core forms at Earth’s center.
F. Earth is a ball of dust, rock, and ice in space.
1.
2.
3.
4.
5.
6.
Answer the following questions on a separate sheet of paper.
7. What were the earliest life forms on Earth like?
8. What hypothesis explains why Earth and the moon are about the
same age?
9. How did photosynthesis lead to the development of animals living
on land?
10. How have scientists used radioactive dating to show that Earth is
about 4.6 billion years old?
Building Vocabulary
Fill in the blank to complete each statement.
11. A(n)
12. The process of
from the sun to make food.
is a ball of dust and ice that orbits the sun.
involves organisms using energy
127D
Name
Date
Class
Early Earth
Read the passage below and then answer the questions that follow in the spaces
provided.
Life and Earth’s Atmosphere
More than 3 billion years ago, an amazing thing happened on Earth. Certain types of bacteria developed
the ability to make their own food. These bacteria made food by using a process called photosynthesis.
Using energy from the sun, the bacteria combined carbon dioxide and water to make food and oxygen.
The oxygen that was given off had a big effect on Earth’s atmosphere.
At first, the oxygen was taken up by iron that was in the ocean water. This caused the iron and oxygen,
or iron oxides, to fall to the ocean bottom and form deposits of iron-rich sedimentary rock. Most of the
iron that is used today to make cars and buildings comes from these deposits. Eventually most of the iron
in the oceans had combined with oxygen and fallen to the ocean floor. Now, oxygen that was produced
by microbes was free to enter the atmosphere. As a result, the oxygen level in Earth’s atmosphere began
to increase significantly about 2.5 billion years ago. Slowly, over hundreds of millions of years, the oxygen
level increased to the present-day level of about 20 percent.
The buildup of oxygen in Earth’s atmosphere allowed the emergence of organisms that cannot exist
without oxygen. Animals, for example, take in oxygen, combine it with the food they eat, and produce
a waste product; carbon dioxide.
1. What advantage does an organism have because of photosynthesis?
2. What gas is given off during photosynthesis?
3. After certain types of bacteria first started producing oxygen, where
did most of the oxygen go?
4. Why was the buildup of oxygen in Earth’s atmosphere important for
animals and other types of organisms?
127E
Name
Date
Class
Early Earth
Write the letter of the correct answer on the line at the left.
1.
According to scientists, both Earth
and the moon are
A about 1.6 billion years old
B about 4.6 billion years old
C about 9.6 billion years old
D about 14 billion years old
2.
After water vapor condensed to form
rain and then gradually accumulated,
which of the following was formed?
A Earth’s first atmosphere
B Earth’s second atmosphere
C Earth’s oceans
D Earth’s continents
3.
Which of the following is not
an important part of Earth’s second
atmosphere?
A helium
B oxygen
C water vapor
D carbon dioxide
4.
The earliest form of life known on
Earth were
A leafy plants
B bacteria
C fossils
D single-celled organisms
Fill in the blank to complete each statement.
5. Scientists believe that
and the moon are about the same age.
6. According to scientists, Earth began as a ball of dust, rock, and
in space.
7.
8. A(n)
pulled this mass together.
is a ball of dust, gas, and ice that orbits the sun.
9. According to scientists, over billions of years, Earth’s
formed, broken apart, and crashed together again.
have
10. Scientists believe that Earth’s core and crust formed after the materials pulled by
Earth’s gravity became very hot and
.
127F
Early Earth
Answer Key
8. When Earth was very young, it collided with
a large object. The collision threw a large
amount of material from both bodies into orbit
around Earth. This material combined to form
the moon.
1. Answers should indicate that the iron filings
gathered on the surface of the paper around
the poles of the magnet.
9. In photosynthesis, oxygen is released as a
2. Answers will vary. Sample: The force of the
waste product. Oxygen released into the air
was changed into ozone, which blocks out
ultraviolet rays of the sun.
magnet was strong enough to attract the
filings from that distance across the paper.
3. Answers will vary. Students may indicate that
10. Scientists used radioactive dating to show that
like the gravity, which pulled materials in space
into a ball, the magnet pulled the iron filings
into a clump.
the oldest moon rocks are about 4.6 billion
years old. Because Earth is slightly older than
the moon, Earth must be roughly 4.6 billion
years old.
4. Answers will vary. Students may indicate that
other planets formed the same way as Earth.
Gravity pulled particles in space into a sphere.
11. comet
12. photosynthesis
Scientists have theorized that Earth began as a
ball of dust, rock, and ice in space; that gravity
gathered these materials, which melted and
formed Earth’s core, crust, and mantle; that many
of the elements of Earth’s atmosphere were added
after it collided with comets; that oceans and
continents later formed; and that 2.5 billion years
ago, photosynthesis finally allowed many organism
to grow.
1. It can make its own food.
2. oxygen
3. Most oxygen was taken up by iron in the
oceans and settled to the ocean floor along
with the iron.
4. Animals and other types of organisms use
oxygen to get energy from food.
1. F
2. E
1. B
2. C
3. D
3. A
4. D
4. A
5. Earth
6. ice
5. C
7. Gravity
8. comet
6. B
9. landmasses
7. They were single-celled organisms that were
probably similar to present-day bacteria.
127G
10. melted
127H