Goals:

1. Explore and model the characteristics of the ocean floor and near shore environments through in-class demonstrations, laboratory activities, and internet research.
2. Use classroom materials to research the characteristics of the ocean floor and report this information to the class.
3. Create a model of a continental margin and use this model to demonstrate ocean processes (tides, waves, sedimentation, etc.)
4. Document laboratory procedures and observations and document internet research in  a lab write-up (suggested format is provided).
5. Write a descriptive paper, in the voice of Timothy talking to blind Philip (from the novels The Cay and Timothy of the Cay), regarding ocean floor characteristics and near shore environments.

Resources:

1. Some ideas from this lesson plan were modified from Chapter 22 of the following resource:
   Alexander, Peter, et.al., Earth Science, Teacher Edition.  Morristown:  Silver  Burdett Company, 1987
2. The following internet site:  http://metosrv2.umd.edu/~owen/EARTHCAST/BUTTONS21/buttons21.html
3. Multiple copies of the following (one for each student):
   Taylor, Theodore.  The Cay.  New York:  Avon, 1969.
   Taylor, Theodore.  Timothy of the Cay.  New York:  Avon, 1993.

 Materials:

1. Each group of students needs the following:
   large (approx. 2í x 2í or larger) rectangular or square transparent basin (plastic  or glass)
   modeling clay
   sand
   water
   sea salt (or table salt if this is not available)
   cementing agent (plaster of paris or powdered clay)
   empty milk carton
   lab write-up worksheet
   dirt

Time:

This lesson will take approximately 7 hours  (Part I:  2.5 hours, Part II:  2 hours, Parts III and IV:  2 hours, Parts IV and V:  1.5 hours)

Procedure:

Part I - Ocean Floor Characteristics
1. As an introductory exercise, instruct the students to examine a topographic map or diagrams of the ocean floor without telling them where the illustrations are from.  The illustrations will show the great variability of the ocean floor such as vast mountain ranges, deep trenches and canyons, gently sloping areas, and areas that are extremely flat.
2. Ask the students to describe what they see in the pictures.  When they are finished, ask them where these features might be found on earth.  (The answers will be quite variable in terms of geography, but they will most likely be some location on land versus  a location in the ocean).  The students will most likely be very surprised that this is a representation of the ocean floor.
3. Briefly describe and illustrate the two main parts of the ocean floor:  the continental margins (underwater areas that border the continents and consist of the three components: the continental shelf, the continental slope, and the continental rise) and the ocean basin floor (the deepest part of the ocean floor away from the continents).
4. Divide the students into groups of 2-3 and instruct the them to research (using textbooks and library materials) and later report to the class the major characteristics of continental margins and the ocean basin floor.  Be sure to give the students some guidance of what information they are expected to find.

 

Note:  The presentations to the class may be formal, which could involve each group being assigned a particular component of the information to be found that they will share with the class.  These presentations could also be informal and involve each group researching all of the information and later actively participating the newfound information in a class discussion.  (The later assessment portion of this lesson will assume a more formal approach.)

Examples:

Continental Margins

continental shelf - begins at the shoreline, is very gently sloping (drops an average of 0.01 m per 1000 m), varies in width from almost nothing to 1600 km (average width is 65 km),  is very rich in natural resources (oil) and is also very nutrient rich.

continental slope-  much more steep (drops an average of 70 m per 1000 m), averages 20 km in width, often contains deep submarine canyons that may or may not be extensions of major river valleys on land and often are the locations of underwater landslides, or turbidity currents.

continental rise-  gently sloping (6 m per 1000 m), contains deep layers of sediment as it accumulates here after moving down the continental slope.
 

Ocean Basin Floor

-begins at the lower end of the continental margin, main features include the abyssal plain, trenches, and seamounts.

abyssal plain - flat areas of the deep ocean floor that are formed when sediment covers any irregularities or rough spots on the ocean floor; these are the most level surfaces on the earth's surface.

trenches - deepest parts of the ocean; long narrow features; up to 11,000 meters below sea level.

seamounts - found on the abyssal plains, underwater volcanoes that sometimes reach the surface of the ocean and rise above sea level.
 

Note:  these are brief descriptions and the students may or may not find much more detail, depending on the resources available.
 

Part II - Construction of Continental Margin Model

1. Inform the students that they will be using lab materials and discuss any necessary safety precautions.
2. Divide the students into groups of 2-3 (can be same groups as before) and provide each group with the necessary materials for this exercise.
3. Instruct each group to work on the following activities simultaneously:
   a)   Constructing a model of a continental margin  - using sand and some cementing agent (clay, plaster of paris, etc.), model the shape of a continental margin, making sure to show all three components.  Also be sure to include a few inches worth of land and form a submarine canyon in the margin that is connected to an on land river valley.  Let the model set to dry. When the model has dried, place a thin layer (.5 cm) of clay over the hardened sand cement form.  Do not place any clay on the surface that represents the land, only cover the continental margin.  Be sure to seal any openings and to seal along the edges to make this water tight.
   b)  Making ìseaî water - on average, sea water has 3.5 % salinity*.  To make a solution of  ìseaî water, use 35 grams of sea salt or table salt for each kilogram (or liter) of water.  Each group needs enough water to cover the ìcontinental marginsî of their models, so an ample amount of salt is necessary to mix with the water.  Also, provide the students with a receptacle to store the water in until it is later used (a five-gallon bucket would work  well).

   * The concept of ocean salinity has been introduced and covered in the Ocean Currents lesson of this unit.  If this particular lesson is observed in isolation, the reader may want to refer to the lesson on Ocean Currents.

4. When the model and the salt water are completely finished, pour the solution of sea water onto the model.  Pour enough sea water on the model so the ìsea levelî is flush with the land-margin interface.
5. Save these finished models for later activities in this lesson.

 

Note: This exercise requires a lot of sand, cementing agent, and salt.   Actual quantities are not given due to the flexibility of the size of the transparent containers.  If the resources are not available for each group to construct a model, the teacher can either make the group sizes bigger or arrange a class activity that involves making one large model where the entire class participates in some way.  Another way to get around not having enough materials is to make the model size smaller (ex. a clear cake pan).
 

Part III - Ocean Deposits

1. Discuss and illustrate to the class the three sources of ocean floor sediment:
   a) from the land either carried to the sea by running water or wind
   b) from the ocean itself through the evaporation of saline water
   c) from the accumulation of shells and other dead organisms hard parts
2. Two of these can be demonstrated using the recently created models:
   a) To demonstrate sediment being carried into the ocean basin from running water, instruct the students to place a pile of dirt and sand on the land portion of the models in the river valley.  Have them run a stream of water (either from a hose connected to a faucet or poured from a container) over the pile of dirt and observe and document what happens to the dirt.
   b) To demonstrate how sediment is derived from the ocean itself, instruct the students to observe the ring of salt that accumulates on the side of the container as the water evaporates.  (It may be a few days before this is observable)
   c) Instruct the students to document any observations they make from this demonstration and all of the demonstrations to follow in a lab write-up (suggested format attached).
3. Another type of ocean deposit is coral reefs.  Discuss and illustrate the formation of  different types of coral reefs:   fringing reefs, barrier reefs, and atolls.   Inform the students that many of the Caribbean Islands were ancient coral reefs that formed as a result of sea level dropping and exposing the reefs. (This will be used more directly in the Travel Brochure lesson of this unit, where the students will be required to study the physical formation of a particular island they will chose).

Part IV - Ocean Waves

1. Introduce the concept of waves by asking the class if they have ever been on a beach or near some body of water where they have seen waves.  Have the students describe what they saw.
2. Describe and illustrate how waves are measured, in terms of wave length and wave height.  After the teacher has described this, ask a student to volunteer to come up and describe it to the class by drawing a wave on the chalk board and pointing out each measurement.
3. Draw a series of waves on the board and have the students use a meter stick to measure the wave lengths and wave heights.
4. Demonstrate waves using the models by showing the students how to create waves in the sea water.  This can be done by using your hand or some flat object to quickly move the water in short repeated movements.
5. Show the effects of waves on a beach environment by placing a long pile of sand on the land portion of the model and recreating the waves.  Instruct the students to observe what happens to the sand on the ìbeachî.
6. Instruct the students to visit the following internet site:  http://metosrv2.umd.edu/~owen/EARTHCAST/BUTTONS21/buttons21.html

   Have the students choose the WAVE HEIGHT - 1995  category.  This category displays the monthly variations for the year 1995 of the global distributions of average wave heights.   Instruct the students to look at each month in detail, to compare the months with one another, and to record their observations in their lab write-ups.
    

Part V - Tides

1. Discuss and illustrate how tides work as a result of gravitational pull on ocean water by the sun and the moon.  Tell the students that the moon has a much greater force on ocean water as compared to the sun, and ask them if they can think of any reason why (ex. the moon is much closer to the earth than the sun, and therefore has a much greater gravitational pull).
2. Display pictures of the same area at high tide and at low tide and have the students describe the difference.  Inform the students that different areas of the world have different tidal ranges.
3. Demonstrate the effect of tides on the land using the model by instructing the students to fill an empty milk carton up with sand and placing it in the water.  The water rising will represent high tide, whereas when the carton is taken out, the lowered water level will represent low tide.

Part VI - Descriptive Paper

1. Instruct the students to write a descriptive paper or a few paragraphs about the following scenario:   Imaging that Timothy and Philip have access to scuba gear with an unlimited supply of oxygen and the equipment that would allow them to dive to the vast depths of the ocean.  Using descriptions of the island from the novel (The Cay or Timothy of the Cay), and the information obtained during this lesson, write a series of paragraphs that give the physical and biological characteristics of a section that begins on the island and ends on the abyssal plain of the ocean.  Be as complete as possible, with the information given, to describe each environment.  Create the writing in the voice of Timothy (not necessarily the dialect, although this would be worthwhile to suggest for those who may be up to the challenge).  Create each description as if Timothy wishes to paint the most vivid picture for blind Philip.

1. Observation of studentsí participation in classroom demonstrations, laboratory activities, internet research, and group activities.  (Criteria for success =  students are actively engaged and work cooperatively with one another and the teacher.  See attached Rubric A)
2. Groups present the  information obtained through research regarding the characteristics of continental margins and the ocean basin floor.  (Criteria for success = presentations are clear to understand, are accurate, and display a clear understanding of continental margins and the ocean basin floor.  See attached Rubric B)
3. Groups complete models of continental margins.  (Criteria for success = models are well constructed and accurately portray a continental margin.  See attached Rubric C)
4. Students hand in lab write-ups of their activities and observations. (Criteria for success = lab write-ups are well-written, neat, contain accurate information, and display a clear understanding of lab activities and internet research.  See Rubric D)
5. Each group turns in their descriptive papers.  (Criteria for success =  papers are creative, well-written, accurate, and display a clear understanding of ocean floor environments.  See attached Rubric E)

1. Language Arts:   lab write up, cooperative group work, presentation of information to the class, descriptive paper
2. Science:   ocean floor characteristics
3. Math:   measurements of the waves, geometric spatial relationships used during   model building

Possible Extensions:

1. Students research for the different types of life forms that live in tidal flats and how some of these life forms are used by humans as food.
2. Students make a comparison graph for spring and neap tides.
3. Discuss different types of beach deposits.
4. Take a field trip to an ocean, lake, or river to demonstrate some of the features discussed in this lesson on a much larger and more realistic scale.
5. Include a lesson on the biological characteristics (flora and fauna) of each environment described.

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Caribbean Cruisers - developed by Sara Bork, Carrie Kriescher, Candice Murphy, & Melissa Randall