Issues in Earth Science
“Eww, There’s Some Geology in my Fiction!”
Issue 3, Mar 2015
Teacher Resources
Suggestions for Activities and Discussions to accompany a Reading of
The Thieving Rain by Anne E. Johnson
Alluvial fans form
where swift streams flowing from hills or mountains encounter a flatter terrain
causing the water velocity to decrease.
When water slows down, some of the sediment gets deposited. The deposit is wedge shaped in
cross-sectional view and fan-shaped in map view.
You can illustrate
this effect with a simple experiment.
Get a short vinyl adjust-a-spout downspout extender and slope it into a
small stream table basin. Put a mixture
of gravel and sand in the downspout and run water through it. Adjust the slope until the sediment begins to
wash downstream. Notice the accumulation
of sediment at the change in slope at the bottom!
If your stream table
doesn't have a fairly large outlet, water will begin to accumulate into a lake
at the base of the slope during this experiment. This will alter the characteristics of your
deposit.
An alluvial fan forms
where the sediment accumulates at a decrease in slope. A delta accumulates where a stream flows into
a standing body of water. In both cases,
sediment is deposited where the water slows down. But the characteristics of the deposits
differ.
Students often
struggle to understand the difference between an alluvial fan and a delta. You might have your students invent an
experimental design to show how the two are different. After creating both types of deposit through
experiment, they could describe the features they see, identifying similarities
and differences between the two.
Beware! Your students might want
to cut a big hole in the side of your stream table so that water doesn't
accumulate. If you love science more
than lab equipment, you might have to let them!
You might want to put
a bucket under the outlet of the stream table so as not to make a terrible
mess—or better yet, make a terrible mess!
Students love that! But
custodians don't, so we recommend the bucket or a sink as used in the
experiments shown below.
It's great
if teachers can incorporate local geological observations into their
classes. Here's an activity that Mary
Colson invented to help students notice and interpret features in NW Minnesota. You can use this activity in your classes as-is,
or you can find something similar from your own area!
In June of 2000,
ten inches of rain fell in a 24-hour period on our farming community in western
Minnesota. Many of the low areas in the
farm fields around our house filled with several feet of water. A few weeks after the rainfall event, we
discovered this tiny pond (see picture below), with an exposed delta and
wave-cut shorelines along with the gully from which the delta’s sediment had
been eroded. Mary and husband Russ
clambered down onto the little delta and pieced together what must have
happened, based on the clues we could see left behind in the farm field.
The tiny
delta and miniature shorelines have long-since been plowed under, but Mary uses
that landscape as a geologic puzzle for her students to practice making sense
of what’s visible in the landscape, to practice applying what they know about
erosion and deposition, and to develop a model that explains how this little
landscape formed.
Overview of the 20-questions game called Earth Stories.
After a Brief Introduction to the landscape, I divide the students into groups of four. Each group has time to examine the photos,
discuss what they see, and come up with two yes/no questions.
During Round One, each group gets to ask me one of
their two questions and everyone listens to my ‘yes’ or ‘no’ or ‘that’s not a
yes/no question’. Students jot down new
information as they hear it. Round One
concludes when each group has had the chance to ask one question. Students then have time to discuss, in their
small groups, what they think they know.
They use the new ideas to formulate two more questions.
During Round Two of questioning, each group can ask
one more question. Their question can be
one of their new questions, or it can be their unasked question from Round
One. Again, students jot down new ideas
and information as they hear them
The End Game consists of each group writing a
paragraph that tells a plausible story for how this landscape developed. The instructions for this part of the game
include the idea that the story is based on observation, not outlandish
make-believe: “Your story should describe, from first to last, the events and
the results that occurred. Your story
should be based on your observations of the features in the photographs and
your explanations for how those features formed.” That evening, I choose a
winning story – the one that is most correct and complete - for each class.
The Next Day, I give the students 12 event cards
that formed the backbone of the story read in the landscape that summer day in 2000. Students put the event cards in order from
first (the oldest event) to last (the youngest event) using logical reasoning
and cross-cutting relationships. We then
discuss the evidence for each event and the reasoning for the ordering of the
events. By the time I announce the
winning team, students already know if their own story was plausible and
complete.
Have students apply the mental model that
they've developed to a new question: Using your
understanding of how the delta formed, can you explain why it has a flat top?
Click here
for a PDF of the game instructions, student worksheets, event cards, and photos
of the landscape.
The
experimental activity and game address a number of NGSS performance expectations,
including the following: MS-ESS 2-1 and MS-ESS 2-2; HS-ESS 2-5. Students can exercise
skills in the practices of 1) planning and implementing investigations, 2) developing
and using models, 3) asking questions, 4) constructing explanations, and 5)
arguing from evidence. Students to
experience the cross-cutting concepts of 1) patterns, 2) cause and effect and 3)
the flow of matter in the Earth system.
———————————————————————————
The Teacher Resources
for The Thieving Rain are written by
Russ and Mary Colson.
Return to
The Thieving
Rain by Anne E. Johnson
Return to “Eww, There’s
Some Geology in My Fiction.”
Find more essays,
games, and stories at
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Science