Activity
Prior to class, set up stations as listed on the
Stations Direction list handout.
Day One
1. Place a pebble or a pile of sand on
your desk or the students’ desks.
Ask students “Who has ever been to
a beach? Was it sandy or pebbly? Where
does that sand or pebble come from?” Most
likely students will respond that the pebbles
and sand are the result of a larger rock
breaking apart. If more appropriate pick
a local example of weathering.
2. “Why or how do rocks break down?” Students
may focus on factors associated with mechanical weathering;
push them to think of other forms of weathering. Write
down all variables identified.
3. Can students distinguish mechanical, chemical and biological
weathering? As a class, divide the factors into groups.
Have students identify how the factors differ once mechanical,
chemical and biological weathering has been identified.
Have students brainstorm variables that might affect each
type of weathering. Record these ideas on the board.
4. Divide the class into groups, Tell students that, for
the sake of time, they will exclude biological weathering
as it encompasses both chemical and mechanical weathering.
At each station they should follow the directions and determine
whether it is chemical or mechanical weathering that is
being demonstrated. Students should also provide a justification
for their choice in their notebooks. They should describe
the action and why it is chemical or mechanical weathering.
5. One all groups have rotated around the stations take
this opportunity to check that they are able to distinguish
between chemical and mechanical weathering. Discuss with
the class which is chemical or mechanical at each station.
6. After the chemical and mechanical erosion station rotation
ask students what are some of the factors that might change
the rate of erosion in different biomes. Students have
studied biomes a little in World Geography so they should
be familiar with differing environments. List on the board
the variables that they come up with. Differing temperatures
and moisture levels will probably come up straight away.
Students might also come up with different forces and temperatures
of wind. Also establish that in some areas rocks might
be different sizes.
7.
Set students the following challenge: ”In your
groups design an experiment which investigates different
rates of one type of erosion in two different biomes. For
example, how do the rates of chemical erosion on a specific
type of rock differ in cold dry environments like the tundra
as compared with a hot dry desert?” (Explain that
in this activity you are trying to ‘model’ a
situation) They are to use the materials available in the
class (see the list above.)Students may well pick two situations
which require that they manipulate multiple variants. Encourage
students who are capable of this to isolate each variable
as well as testing as a whole. For some students it is
best to focus on just one variable.
8.
When planning their experiment students should develop
an “if”…”then” hypothesis
based upon their earlier observations. If they have multiple
variants they should develop multiple “if”…then” statements.
They should create a data collection instrument that addresses
the “if….then” statements and a protocol
to test each one. Let them work on this for the remainder
of class. They should be ready to work on this tomorrow.
Day Two
9. Before students proceed with their initial tests, groups
should get approval for their experimental design and data
collection sheet.
10. Allow students the rest of the day to complete their
experiment.
11. Assign Homework – meet with your group to prepare
a brief presentation sharing what you have found.
Day Three
12. Have students meet for a few minutes to finalize their
presentations.
13. Have groups present their protocols (methods) and results.
14. As groups are presenting, the students in the audience
need to record data from the other groups. Each student
should be able to describe the general results for each
of the other groups in their science notebook. How were
the results different than theirs? The same? Why? Be sure
to have students do more than just say that different results
for different types of weathering are due to that fact
alone.
Closure
Make
sure that you leave enough time for this piece, as it
is important. Remind students that they have been studying
biomes in Social Studies. Ask the students in what type
of biome might they see each type of weathering. Why?
In a rain forest, there would be some chemical erosion
due to rain dissolving the chemicals that make up the
rocks, etc.)
Embedded
Assessment
Can students identify the ways in which
chemical and mechanical weatherings differ?
This is another opportunity to have students complete
a formal laboratory report. An example of how to guide
students in this can be found at: http://www.wilson.wnyric.org/t/drobison/labshare/davidrobison/weathering.pdf
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