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Teaching Note:
How living things respond to the tremendous pressures
that occur at the bottom of oceans fascinates students
and teachers alike. The following activities facilitate
student learning about the relationship between depth and
pressure as well as the effects of those pressures on humans
and animals. This activity can be done as a class
presentation or as an individual or group challenge.
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Materials:
- 2 containers into which you can punch holes (plastic milk
jugs, milk cartons, soup cans, one gallon cans, #10 food
cans)
- Something to punch holes in those containers (hammer and nails, pen or
pencil)
- 1 ruler
- 1 sink or large bin in which to catch water
- adhesive tape
- water
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Teaching Note:
Run the experiment in advance of class with
another pair of containers. Determine an appropriate distance
between holes, as well as how much water will be dispensed into
the collection sink or bin. It is important to have appropriately
sized holes as well. If the holes are too small, the
water will dribble out, and if they're too big, the water
will pour out too fast to allow accurate measures.
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Suggested Lesson:
Ask, "Where is water pressure greater, at the top of the ocean or on the
ocean floor?" Ask students to explain their responses. Record responses
and the students' reasons for giving them.
For small group experimentation, give groups of students the following
task, and then have them report back to the class:
"Using the following materials (two containers,
hole-punching tool, tape, ruler, water bin, water), design an
experiment that demonstrates one of the following:
- As depth increases, pressure increases
- As depth increases, pressure stays the same
- As depth increases, pressure decreases
Allow students time to discuss, experiment, and record results.
For whole class demonstration:
Punch three holes into each container. In the first container, punch a
vertical row of holes a couple of inches apart. In the second
container, punch a horizontal row of holes a couple of inches
apart. Place the containers in the sink or large bin and place
one piece of tape across each row of holes. Fill the containers
with water. Remove the tape from each container one at a time in a
swift motion. Note the length of each stream as the water spews
from the container.
For a more scientific or accurate measure of stream length, turn
each container so that the holes are pointed to the right of the
audience (students). Place a piece of graph paper or a ruler
behind each container. (Darken the lines with a marker so
that they can be seen easily.) Have one student note the length
of each stream of water. Point out that the graph paper/ruler acts as
a stream meter or pressure guage against which the student is able
to measure the relative strengths of the two streams.
Questions for Discussion or Written Reflection:
- Which container had varying stream lengths?
- Which hole projected the longest stream of water? Which had the
shortest?
- Did the horizontal or vertical row of holes have the same stream
lengths?
- Were our original predictions true?
- Which is proven:
- As depth increases, pressure increases?
- As depth increases, pressure stays the same?
- As depth increases, pressure decreases?
- How does our knowledge of the depth/pressure relationship affect
deep-sea research?
- How does depth/pressure affect the type of sea life we find as we
travel towards the bottom of the ocean? How do animals and plants adapt
to the intense pressure of deep ocean habitats?
- Pressure at sea level is 14.7 pounds per square inch. What is the
progression of pressure increase as we move to one mile below
the surface? Does salinity or temperature affect the amount of pressure
or how fast it increases? If so, how might we measure their effects?
- What is the best shape for a deep sea instrument housing or
submersible? "Best" refers to the strongest shape for the thickness of
the material.
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