LESSON PLAN
Name: Allyson
Berglund
Title of lesson: Finding Impact Craters
Date of lesson:
Length of lesson: 120 minutes
Description of the class:
Name
of course: Science
Grade
level: 8
Honors
or regular: Regular
Source of the lesson:
http://craters.gsfc.nasa.gov/summary.html
A
NASA classroom activity
TEKS addressed:
(11) Science
concepts. The student knows that traits of species can change through generations
and that the instructions for traits are contained in the genetic material of
the organisms. The student is expected to:
(A) identify that change in environmental conditions can affect
the survival of individuals and of species;
(13) Science
concepts. The student knows characteristics of the universe. The student is
expected to:
(C) research and describe historical scientific theories of the
origin of the universe.
(14) Science
concepts. The student knows that natural events and human activities can alter
Earth systems. The student is expected to:
(A) predict land features resulting from gradual changes such as
mountain building, beach erosion, land subsidence, and continental drift;
(B) analyze how natural or human events may have contributed to
the extinction of some species; and
I. Overview
Students then read
descriptions of the actual effects of impact events and the evidence these
leave behind. The students will concededly fill out KWL chart to help with
their reading. In small groups, they
study satellite images that show possible evidence of impact events. In their
interpretations, they explain how the image does or does not show evidence of
an impact event. To demonstrate their understanding of the role of impact
events in shaping the Earth, students write a series of guidance questions for
a field expedition to determine whether or not a given landform is an impact
crater.
II. Performance or learner outcomes
Students
will be able to:
Describe the effects of extraterrestrial objects
upon the Earth's surface
Describe the role of satellite technology in
helping scientists to identify evidence of impact events
Describe why and how science is an ongoing
process of discovery
III. Resources, materials and supplies needed
For each group of students:
Aerial
photograph of Barringer Meteor Crater
IV. Supplementary materials, handouts.
For each student:
KWL charts
Known Effects of Impact Events
Describing Satellite Images of
Possible Impact Craters
Questions You Would Ask on a Field
Expedition to a Possible Impact Crater
Satellite images of landforms with
pseudonyms for student use
(Students may recognize some names
and know already whether or not they're impact craters.)
Aorounga
(Aor)
Elgygytgyn
(Elg)
Haughton
(Hgh)
Manicougan
(Man)
Mount St.
Helens (Msh)
Richat (Rch)
Schooner
(Sch)
Five-E
Organization
Teacher
Does Probing Questions Student
Does
Engage: Learning Experience(s) How students the picture
of Barringer Meteor Crater located in
|
Critical
questions that will establish prior knowledge and create a need to know Ask students if any of
them have visited Barringer Meteor Crater. |
Expected
Student Responses/Misconceptions Students who have done so
can describe their experience. |
Explore: Learning Experience(s) Pass out KWL chart Distribute the Student Worksheet, "Known
Effects of Impact Events". Students describe the effects of an impact on Earth |
Critical
questions that will allow you to decide whether students understand or are
able to carry out the assigned task (formative) Ask
students to fill in the What I know about craters section. Ask
students to fill in the What I want to know about crater section. Tell students to read quietly
the description of what happens during an impact. Ask students to fill in
the What I learned portion of the crater KWL chart. |
Expected
Student Responses/Misconceptions Formed
by meteors, round, fake, old, found everywhere, extinction of dinosaurs How
are craters formed, are big are craters, how do they last so long, will
another crater form in our lifetime Explosion,
heat, makes a big hole with rim, fires, shockwave, vaporizes water |
Explain: Learning Experience(s) Organize students in small groups and distribute the following: (1) One set of seven satellite images to each group
Monitor the student groups as they discuss their analyses of the satellite images. |
Critical
questions that will allow you to help students clarify their understanding
and introduce information related to concepts to be learned Ask student groups to determine whether or not the
landforms in all seven of the images appear to be impact
craters. As groups discuss their
analyses of the images, make sure they are discussing the evidence
constructively with each other. |
Expected
Student Responses/Misconceptions Mount |
Extend / Elaborate: Learning
Experience(s) Questions You Would Ask on a Field Expedition to a Possible Impact
Crater |
Critical
questions that will allow you to decide whether students can extend
conceptual connections in new situations Ask students to write a set of questions for
researchers going on a field expedition to an unidentified landform. The
questions should serve well as guidance to determine whether or not the
landform could be positively identified as an impact crater. |
Expected
Student Responses/Misconceptions Show evidence that you
have a full and complete understanding of how an impact event can shape the
land, soil, and surrounding rocks, as well as the atmosphere and living
things |
Evaluate: Lesson
Objective(s) Learned
(WRAP ≠UP at end) -> Summarize Have
students fill in extra information n What I Learned Ask
students to share what learned with the class |
Critical
questions that will allow you to decide whether students understood main
lesson objectives What are the causes of
craters? What are factors that
influence how craters form? Name some craters that can
be identified with a satellite. |
Known
Effects of Impact Events
When an object from space hits the Earth
More About ...
More About Impact Events in General
Impact craters are
geologic structures formed when a large meteoroid, asteroid or comet smashes
into a planet or a satellite.
A very large number of meteoroids enter
the Earth's atmosphere each day, amounting to more than a hundred tons of
material. They are almost all very small, just a few milligrams each. Only the
largest ones ever reach the surface. The average meteoroid enters the
atmosphere at between 10 and 70 km/sec. All but the very largest are quickly
decelerated to a few hundred km/hour by atmospheric friction, and they hit the
Earth's surface with very little fanfare. However meteoroids larger than a few
hundred tons are slowed very little; only these large (and fortunately rare)
ones make craters.
All the inner bodies in our solar system
have been heavily bombarded by meteoroids throughout their history. The
surfaces of the Moon, Mars and Mercury, where other geologic processes stopped
millions of years ago, record this bombardment clearly. On the Earth, however,
which has been even more heavily impacted than the Moon, craters are continually
erased by erosion and redeposition as well as by volcanic resurfacing and
tectonic activity. Thus only about 120 terrestrial impact craters have been
recognized, the majority in geologically stable areas of
More About the
Energy Released by Impact
Energies of impact are
almost incomprehensibly large. They come chiefly from the kinetic energy of the
impacting object. An object only a few meters across carries the kinetic energy
of an atomic bomb as it strikes another object at high velocity. The impact of
an object only a few kilometers across (smaller than many known asteroids and comets)
can release more energy in seconds than the whole Earth releases (through
volcanism, earthquakes, tectonic processes, and heat flow) in hundreds or
thousands of years.
More About
Extraterrestrial Objects in the Solar System
Thousands, possibly millions,
of objects move throughout the solar system, orbiting the Sun. They range from
microscopic dust particles to objects tens of kilometers across. Each object
moves in its own orbit. We don't know how often they have hit the Earth in the
past.
More About Impact Velocity
The minimum impact velocity for collisions with Earth is 11.2 km/s. This is
equal to the escape velocity for an object launched into space from Earth's
surface.
More About the Sizes of Craters
Objects of less than half a kilometer in diameter can make craters 10 km in
diameter.
More About Crater Shapes
Nearly all impact events result in circular craters. In rare cases where the
angle of impact was very low (0-10 degrees from the plane of the horizon),
craters can be ovoid in shape.
More About Finding Impact Craters on the Ground
When looking for impact craters in satellite images, first pay attention to
circular features in topography or bedrock geology. Look for lakes, rings of hills, or
isolated circular areas.
On the ground, look for changes in the
physical properties of the rocks in and around impact structures. Fractured
rock is less dense than unaltered target rock around the structure. Also look
ejecta and shocked rock fragments on the original ground surface outside the
crater, and for fragments of the meteorite.
Name:____________________
K-W-L Worksheet for Formation of Crater
K What I know |
W What I want
to find out |
L What I
learned |
|
|
|
Describing Satellite Images of Possible Impact Craters
A. The object itself: Would you expect to see any evidence of the object
itself in a satellite image? What evidence might you find?
_________________________________________________________________________________________
_______________________________________________________________________________________
B. Shape of the land: What kinds of changes would that impact make to the shape
of the land where it hit, and all around?
_________________________________________________________________________________________
_________________________________________________________________________________________
C. Effects of Time: What kinds of changes will occur to the impact site over
time? Remember that some changes are fast, and some are slow.
_________________________________________________________________________________________
_________________________________________________________________________________________
D. What else might you see in these satellite images that could help you learn
about an impact crater?
________________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
Part II. As a group, study all of the satellite images. Below are their fake names (to use until you've identified them yourselves as impact craters or something else):
AOR
Latitude: N 19° 6'
Longitude: E 19° 15'
Size: 12.6 km in diameter
ELG
Latitude: N 67° 30'
Longitude: E 172° 5'
Size: 18 km in diameter
HGH
Latitude: N 75° 22'
Longitude: W 89° 41'
Size: 20 km in diameter
MAN
Latitude: N 51° 23'
Longitude: W 68° 42'
Size: 72 km in diameter
MSH
Latitude: N 46° 16'
Longitude: W 122° 12'
Size: several km in diameter
RCH
Latitude: 21°04'N
Longitude: 11°22'W
Size: 38 km in diameter
SCH
Latitude: N 37° 20' 36.1"
Longitude: W 116° 33' 59.9"
Size: About 300 m in diameter
You need to know that
All of these satellite images show the Earth's land surface, not another planet's surface, and not the Earth's atmosphere. No hurricanes or tornadoes appear in these images.
The colors in these images are false colors. White isn't always snow; lakes often appear black; vegetation is sometimes red.
All of these landforms are large. One is 300 m in diameter, and the others are 1 km in diameter or larger. Most of them 10-90 km in diameter.
Aliens from other parts of the universe had nothing to do with creating the landforms in these images.
If you see a letter or a face, it's just an accident of nature.
People sometimes make large craters with explosives or large mining equipment.
Multiple Impacts: Sometimes impacts come in twos or threes. It's rare, but it can happen when a comet or asteroid breaks into a couple of large pieces just before it strikes the Earth.
Part III. As a group, now choose two of the images you find most interesting.
AOR ELG HGH MAN MSH RCH SCH
B. What evidence do you see in the satellite image that your landform is or is not an impact crater? Describe it here:
_______________________________________________________________________________________
_________________________________________________________________________________________
_________________________________________________________________________________________
Come to agreement as a group about whether or not the image you've chosen is or is not an impact crater, and why.
Questions
You Would Ask
on a Field Expedition to a Possible Impact Crater
Identifying what might be an impact crater in a satellite image is only the
first step in identifying it with 100 percent certainty. That requires people
making a field expedition to gather and study evidence at the site itself.
Field expeditions cost money. Getting money nearly always requires writing
excellent grant proposals. You have to prove you understand the science and
know what you're doing before people will give you the money to do it.
Your task is to write a series of questions you would use to guide a field expedition to determine whether or not a given landform was an impact crater.
You will do well on this learning assessment if you:
Show evidence that you have a full and
complete understanding of how an impact event can shape the land, soil, and
surrounding rocks, as well as the atmosphere and living things;
Use terminology accurately;
Explain your ideas in ways that makes sense;
Use complete sentences.