Earth’s Catastrophic Past: Teacher’s Guide
Grade Level: 6-8
Curriculum Focus: Earth Science
Lesson Duration: Two class periods
Program Description
Discover the devastating forces that pummeled primitive Earth and helped create the conditions
for life to flourish. Revisit the supercontinent Pangaea and watch scientists track its splitting up
into our present-day continents. Today we enjoy a geologic truce of relative stability, but we
ponder the future of our restless planet.
Onscreen Questions
Part I—Before watching the video
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As a class, discuss what you already know about how Earth was formed.
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What type of geologic events do you think led to the formation of the continents, the oceans,
and the atmosphere?
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As you watch the program, keep track of the evidence that scientists use to formulate theories
about what shaped our plane?
Part I—After watching the video
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Geology can be defined as the science dealing with the formation and structure of Earth.
Discuss how geology has increased our understanding of Earth’s biological history. Use
examples from the documentary to illustrate your points.
Part II—Before watching the video
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Environmental scientists believe that the continents were once joined together in one
supercontinent. While you watch the documentary, keep track of the evidence that supports
this theory.
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What events might have led to the separation and the unique landscaping of Earth’s
lithosphere?
Part II— After watching the video
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The documentary highlights several different research efforts aimed at creating a picture of
Earth’s past. Choose one of these studies and make a list of the supporting evidence presented
in the documentary.
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Is the evidence convincing to you?
Life Cycles: Teacher’s Guide
2
Lesson Plan
Student Objectives
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Research when a group of organisms first appeared on Earth.
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Create part of a classroom frieze documenting life on Earth.
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Give a brief report to the class.
Materials
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Earth’s Catastrophic Past video and VCR
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Computer with Internet access
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Library materials on the history of life on Earth
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A long, narrow sheet of paper to create a wall frieze that extends around the entire classroom
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Paper, pens
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5" x 7" index cards
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Markers
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Tape
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Scissors
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Paste
Procedures
1. Encourage students to share what they have learned about the history of Earth and the
catastrophic forces—both extraterrestrial and terrestrial—that over the eons created the right
conditions for life and sculpted the planet into the home we know today.
2. Tell students that they are going to create a time line of life on Earth.
3. Assign one of the following organisms or groups of organisms to each student, or have students
work in pairs and make assignments to pairs. (Note: With permission, students may substitute
an organism or group of organisms of their choice. Make sure that the following categories are
covered.)
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bacteria
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plants
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invertebrates
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fish
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amphibians
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reptiles
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birds
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Life Cycles: Teacher’s Guide
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mammals
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Java man
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Peking woman
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Australopithecus boisei
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Neanderthal man Detect termites in buildings
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Cro-Magnon man
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modern-day humans
3
4. Encourage students to use library materials and the Internet to research their topic. The
following Web sites have useful information.
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History of Life on Earth
http://seaborg.nmu.edu/earth/Life.html
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A Brief History of Life
http://www.pbs.org/wgbh/nova/link/history.html
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Palaeos: The Trace of Life on Earth
http://www.palaeos.com
5. Tell students they must find out how long ago their organism first appeared on Earth. Instruct
them to take notes and gather information containing at least 10 facts about their organism for a
brief report to the class. These facts may include
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the name of the geologic period in which the organism first appeared;
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the organism’s scientific name;
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other life forms living during this period;
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Earth’s environment during this period; and
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how the organism lived.
6. Distribute index cards to students. Have them use markers to write on their card the name of
their organisms and the approximately how long ago they appeared on Earth (for example,
“bacteria—3.6 billion years ago,” or “birds—200 million years ago”). Students should also
include simple line drawings or use pictures from magazines to illustrate their life forms. (They
may draw organisms such as bacteria as seen under a microscope.)
7. Use narrow paper to create a frieze that stretches around the classroom. Students will use the
frieze to create their time line. Make sure they understand that the length of the time line
reflects Earth’s estimated age of 4.6 billion years.
8. How to divide the time line for a classroom with four walls:
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Use one wall to represent 4.6 to 3.6 billion years ago.
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Use the second wall to represent 3.6 to 2 billion years ago.
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Use the third wall to represent 2 to 1 billion years ago.
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Life Cycles: Teacher’s Guide
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4
Use the fourth wall to represent the most recent billion years. Divide this wall into
tenths, with each tenth representing one hundred million years.
9. Explain that the scale is not precise because the numbers delineating Earth’s history are so large,
but it should give an idea of relative time periods.
10. Have students tape their index cards to the appropriate part of the time line. As they do this,
have them give a brief report to the class about the life forms.
Assessment
Use the following three-point rubric to evaluate students’ work during this lesson.
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3 points: Students actively participated in class discussions; demonstrated an ability to
conduct research diligently and thoroughly; created an index card with accurate
information and images of an organism or group of organisms; placed the card correctly on
the time line; gave an informative report to the class about the organism.
•
2 points: Students participated somewhat in class discussions; demonstrated an ability to
conduct on-grade research; created an index card with accurate information and images of
an organism or group of organisms; placed the card correctly on the time line; gave a
somewhat informative report to the class about the organism.
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1 point: Students participated little, if at all, in class discussions; had difficulty conducting
research; created an index card with some accurate information and images of an organism
or group of organisms; placed the card incorrectly on the time line; gave a less than
informative report to the class about the organism.
Vocabulary
asteroid
Definition: One of a group of small, planet-like bodies whose general orbit around the sun lies
chiefly between Mars and Jupiter
Context: Asteroids probably originated from meteorites.
basalt
Definition: A hard, dense, dark volcanic rock, often having a glossy appearance
Context: An igneous rock found in remnants of lava flows, basalt helps geologists determine the
relationships of landmasses and rock formations.
lithosphere
Definition: The crust and upper part of Earth’s mantle; Earth’s outer shell
Context: The lithosphere carries the continents and is made up of different strata of rocks
extending 60 miles down into Earth.
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Life Cycles: Teacher’s Guide
5
meteorite
Definition: Matter that has fallen to Earth from outer space
Context: Meteorites provided the rock material necessary for the Earth to grow.
Pangaea
Definition: A hypothetical supercontinent that included all the landmasses on Earth before the
Triassic period
Context: When continental drift began some 200 million years ago, Pangaea split into two
supercontinents.
plate tectonics
Definition: A theory that explains geological phenomena such as seismicity, volcanism,
continental drift, and mountain building in terms of the formation, destruction, movement, and
interaction of the Earth’s lithospheric plates
Context: Plate tectonics is a process that is still going on today, believed to be the cause of
earthquakes, volcanoes, and other geologic events.
Academic Standards
National Academy of Sciences
The National Science Education Standards provide guidelines for teaching science as well as a
coherent vision of what it means to be scientifically literate for students in grades K-12. To view the
standards, visit http://books.nap.edu.
This lesson plan addresses the following science standards:
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Earth and Space Science: Earth’s history
Mid-continent Research for Education and Learning (McREL)
McREL’s Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education
addresses 14 content areas. To view the standards and benchmarks, visit http://www.mcrel.org/.
This lesson plan addresses the following national standards:
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Science—Life Sciences: Understands relationships among organisms and their physical
environment; Understands biological evolution and the diversity of life
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Language Arts—Viewing: Uses viewing skills and strategies to understand and interpret
visual media; Reading: Uses reading skills and strategies to understand and interpret a
variety of informational texts
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Life Cycles: Teacher’s Guide
6
Support Materials
Develop custom worksheets, educational puzzles, online quizzes, and more with the free teaching tools
offered on the Discoveryschool.com Web site. Create and print support materials, or save them to a
Custom Classroom account for future use. To learn more, visit
•
http://school.discovery.com/teachingtools/teachingtools.html
Published by Discovery Education. © 2005. All rights reserved.