Biology/Chemistry
Rock
Formation.
Therese
Donatello |
St. Edward
School |
4343 W.
Sunnyside |
|
CHICAGO IL
60630 |
|
(773)
736-9133 |
Objective(s):
The
Junior High student will be able to show how rocks are formed by
cementation,
compaction, and evaporation.
Materials:
EVAPORATION; Each group will need 2 test
tubes, 40mL of water, 3-4 teaspoons of salt, 3-4 teaspoons sugar, 2
toothpicks,
2 pieces of string, and 2 plastic caps.
CEMENTATION; Each group will need 2
plastic cups, 1 jar large enough to hold the plastic cup, enough sand
to fill
the cup ¾ full, enough white glue to fill a cup ½ full, enough water to
fill
the cup with the glue, and a stick.
COMPACTION:
Each group will need a
pencil sharpener, 4-5 crayons of different colors, and a 12 inch piece of aluminum foil.
Strategy:
EVAPORATION:
A. Place 20 mL of water into each test tube. In one container add salt until no more will dissolve. In the other test tube add sugar until no more will dissolve.
B. Pour a thin layer of each
solution into separate plastic caps.
C. Tie a string to one end
of a toothpick and place the other end of the thread into the test tube
so it
doesn’t touch the sides or the bottom of the test tube.
D. Place the test tubes and
the plastic caps where they will not be disturbed.
E. Check the solutions daily
and record any changes.
CEMENTATION:
A. Poke small holes into the bottom of a plastic cup that will let a solution flow through but not the sand.
B.
Fill a cup ¾
full of sand.
C.
In a second
cup mix ½ cup
white glue with ½ cup water.
D.
Suspend the
cup with the
sand over the jar.
E.
Slowly pour
the glue
solution over the sand and allow it to drain through for several days.
F.
Cut away the
cup when the
sand feels dry to the touch and record the results.
COMPACTION:
A.
Use a pencil
sharpener to
make a pile of crayon shavings (use different colors to represent the
different
minerals) on a sheet of aluminum foil.
B.
Fold the
edges of the foil
to make a rectangular packet.
C.
Gently
flatten the packet by
squeezing it between your palms.
D.
Unfold the
packet and
examine the “rock” that was formed.
E.
Return the
“rock” to the
foil packet and stand on it. Then open
and examine it again.
Performance Assessment:
The student should be able to answer the following questions.
A.
In the
evaporation
experiment compare what happened to the thin layer solution and the
solution in
the test tube.
B.
In the
compaction experiment
explain what kind of rock was formed giving at least three reasons.
C.
In the
compaction experiment
explain what happened as more pressure was applied to the packet of
crayon
shavings.
D.
Based on
what you know about
heat and rock formation what do you think would happen to a packet of
crayon
pieces that was heated on a hot plate for three or four minutes. Tell what the crayon pieces represent and
what kind of rock was formed.
Conclusions:
The
student will be able to explain the formation of rocks by the various
methods
described and infer the formation of other rocks when given information
for
another type of experiment.