8.2
Putting Together the Pieces of a Puzzle
Time
PRESCRIBED LEARNING OUTCOMES
30–45 min
• explain how Earth’s surface changes over time
Key Ideas
SKILLS AND ATTITUDES
Wegener developed his
theory of continental drift
using available evidence—
the shapes of the continents,
the fossil record, landforms,
and an ancient ice age.
• investigate the use of models to show large scale systems
Vocabulary
Page 221
ICT OUTCOMES
• apply predetermined search criteria to locate and retrieve information
using information technology tools
• analyze information retrieved from a variety of electronic sources
• Pangaea
Program Resources
SCIENCE BACKGROUND
SM 8.2 Putting Together the
Pieces of the Puzzle
BLM 8.2-1 Pangaea Puzzle
Nelson Science Probe 7
Web site
www.science.nelson.com
• Pangaea was a large supercontinent
that existed approximately 225 million
years ago. Pangaea started to break
up about 200 million years ago, and
the pieces started to move away from
each other. This movement, called
continental drift, continues today.
• During the Jurassic period (206 to
144 million years ago) two smaller
supercontinents formed—Laurasia
and Gondwanaland. Gondwanaland
formed in the southern hemisphere
and included what are now the
continents of South America, Africa,
India, Australia, and Antarctica. So a
land mass that may have been closer
to the equator ended up forming the
continent of Antarctica.
• Wegener’s theory of continental drift
is supported by biological evidence:
– African dromedaries and South
American llamas are very much
alike.
– The American jaguar and the African
leopard seem closely related.
– Freshwater pike are very similar in
Europe and North America.
• His theory is also supported by
distribution of animals:
– Amphibians and reptiles first
appeared during the time of the
supercontinent and are widely
distributed on practically every
continent today.
– Mammals did not appear until after
the breakup of the supercontinent
and each type of mammal tends to
be found on a single continent.
Exceptions to this (e.g., moose
found in North America and
Europe) can usually be explained
by land bridges that existed until
recent times and allowed for the
migration of animals under certain
conditions.
• Wegener believed that the theory of
continental drift not only explained
the fossil records of identical plants
and animals on different sides of the
ocean, but also the dramatic climate
changes experienced on some
continents. For example, fossils of
tropical plants found in coal deposits
in Antarctica support the idea that it
was once situated closer to the
equator in a more temperate climate.
TEACHING NOTES
• Students will probably not think of a scientist developing a theory in a
human interest sense. That is, they can see and appreciate the
usefulness of models representing theories/concepts, but they may not
connect this to the personal events that occurred as scientists like
Wegener painstakingly pieced together years of observations and
evidence, only to be rejected by their peers. Emphasize this aspect of
science as students work through Section 8.2.
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Unit C: Earth’s Crust
NEL
• Some students and their families may hold religious beliefs that
disagree with the scientific theories described in this chapter. In
dealing with religious beliefs, comply with provincial curriculum and
district policies.
1 Getting Started
• Check for Misconceptions
– Identify: Most students believe that continents are too big (massive)
to move. The idea that a landmass can change position is still
probably a little far-fetched for some students, even after reading
Section 8.1.
– Clarify: Reinforce that the evidence gathered and the observations
made by scientists support this theory. Emphasize that continental
drift occurs over millions of years and therefore is not directly
observable. Scientists have to depend on indirect evidence.
– Ask What They Think Now: At the conclusion of Section 8.4, revisit
the misconception by asking how many students at first thought
that continents were in a fixed position, but now understand that
they do move over time.
• Have students turn to the Skills Handbook and read the section
Thinking Like a Scientist. Discuss the three reasons given for
conducting investigations. Although it is not explicitly addressed in
the Skills Handbook section, explain to students that scientific
investigations do not always include scientific experiments.
Investigations of Earth’s history cannot be carried out using
experiments, but rely largely on models and the collection and
analysis of indirect evidence.
2 Guide the Learning
• Read the first two paragraphs with students and review the Learning
Tip. Ask students if they think Pangaea was a good name for the
supercontinent and why.
• Focus students’ attention on Figures 2 and 3 and use Reading and
Thinking Strategies: Interpret Visuals and Graphics to reinforce
how to read a map legend.
• Ask students if Wegener’s observations supported his theory of
continental drift. Ask which pieces of evidence they think best
support his theory and why.
• For students who need additional support with the reading in this
section, use SM 8.2 Putting Together the Pieces of the Puzzle.
3 Consolidate and Extend
• Read the final Learning Tip, and have students answer the question.
(The striations are caused by rocks in the ice.) Ask what other things
they have learned that can be connected to the information in this
section (e.g., how fossils are formed).
• Assign the Check Your Understanding questions.
NEL
Chapter 8
Earth’s crust is made up of moving plates.
407
CHECK YOUR UNDERSTANDING—SUGGESTED ANSWERS
1. Wegener used the following evidence to support his hypothesis that the
continents had once been joined in one supercontinent: The continents of South
America and Africa fit together like pieces of a jigsaw puzzle. Fossil records
showed identical plants and animals on different continents. Mountain ranges in
South Africa matched up with mountain ranges in Argentina. Rock formations
and coal deposits in South Africa were the same as in Brazil. Mountains in the
eastern United States matched those in Scotland. The patterns of glacier
striations were the same on rock surfaces in South America and South Africa.
Deposits left by glaciers during an ice age were the same in Africa, India,
Australia, and Antarctica.
Technology Connections
Have students further
research the theory of
continental drift. As
students do their research,
ask them to identify Web
sites they found
particularly helpful and
what it was about those
Web sites that made them
good sources of
information.
2. The weakness in Wegener’s theory of continental drift was that he could not
explain what made the continents move. He did not know the cause of the
movement.
LEARNING TIP
Reading and Thinking Strategies: Interpret
Visuals and Graphics
When reading maps,
remember to check the
legend to find out what the
different symbols or colours
on a map represent.
Meeting Individual Needs
• Direct students’ attention to Figure 2. Have them
read the caption and scan the map.
• Have them look at the legend and point out on the
map where fossils of Mesosaurus and Glossopteris
are found. Ask them what the symbols for these two
fossils tell them. (Mesosaurus was an animal, and
Glossopteris was a plant).
• Direct students’ attention to the legend in Figure 3,
and have them locate the mountains and coal
deposits on the map. Ask them to explain the
difference between this legend and the legend for
Figure 2. (Figure 2 uses symbols and Figure 3 uses
colour to show different things.)
Extra Support
• For students who need additional support with the reading in this
section, use SM 8.2 Putting Together the Pieces of the Puzzle.
Extra Challenge
• Have students use BLM 8.2-1 Pangaea Puzzle and conduct research to
make their own map of Pangaea.
www.science.nelson.com
GO
ASSESSMENT FOR LEARNING
What To Look For in Student Work
Suggestions for Teaching Students Who Are Having Difficulty
Evidence that students can
• describe Wegener’s theory of continental
drift, including the evidence used to
support his theory, and explain why his
theory was not accepted
• use technical language correctly
(Pangaea)
Work with students in a group to summarize, in jot notes, what they learned about
each piece of evidence.
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Unit C: Earth’s Crust
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