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Voyage of Doom

Classroom Activity

Objective
To design and construct a simple cofferdam and consider the advantages and disadvantages of modeling.

• copy of "Build A Cofferdam" student handout (HTML)
• scissors
• 1-gallon (4-liter) milk jug, with the top third cut off, leaving about 6 inches (15 centimeters) in height
• 101-fluid ounce (3-liter) soda bottle, top and bottom cut off so that the remaining cylinder is 6 inches (15 cm) high
• 68-fluid ounce (2-liter) soda bottle, top and bottom cut off so that the remaining cylinder is 6 inches (15 cm) high
• soup ladle or other device to remove water
• pair of forceps or tongs
• sand
• water
• small objects such as marbles, dimes, and pennies

1. Once students have seen the program, discuss the principles of how the cofferdam kept most of the water from re-entering the site once it was pumped out.

2. Organize students into groups and distribute the "Build a Cofferdam" student handout. Lay out one set of the supplies. Have students talk through the requirements listed on their student handout and consider whether they would like any additional materials added to the existing list.

3. Before students begin building, have each group design its cofferdam on paper.

4. Once you have checked their designs and helped students problem solve any major obstacles, distribute materials to each group and have students execute their design. Have students keep a record of their progress.

5. Once the cofferdam is built, have students recover their artifacts, map where the artifacts were in relation to each other, and describe and record each artifact in their journal.

6. Have a class discussion about how well each cofferdam worked and what students might do differently if they were to build it again.

7. To complete the lesson, have students assess their model in terms of how accurately they portrayed a full-scale cofferdam. What does the model show that would be useful for engineers? What does the model not take into account?

To construct a cofferdam out of the materials provided:

1. Pour sand in the milk jug to a depth of about 2 inches (5 centimeters).

2. Push three or four small objects into the middle of the container of sand. Pour water in to a depth of about 4 inches (10 centimeters).

3. Push the 101-fluid ounce (3-liter) bottle cylinder into the sand until it reaches the bottom of the milk jug. This simulates the outer wall of the cofferdam. Place the 68-fluid ounce (2-liter) bottle cylinder inside the larger cylinder and push it into the sand. This simulates the inner wall.

4. Fill the space between the cylinder walls with sand. Make sure the water level inside and outside the cofferdam is equal. Use the ladle to empty the water from inside the smaller cylinder. (Some water is likely to leak back in and will need to be pumped back out as with the cofferdam seen in the program.) Use forceps or tongs to recover the artifacts.

Some similarities between the model and the final structure include the sand, water, and objects to recover. Some factors not modeled include water pressure outside the dam, testing for the most suitable diameter between the cofferdam walls, the most suitable materials needed to build the structure, and the effect of tides, rain, and storms. While many factors are not simulated, the model is still useful to brainstorm and problem solve potential pitfalls in building a cofferdam and pumping out water.

Cofferdams have many uses, including in the construction of bridges, piers, building foundations, sewer or water lines, and pumping stations; or to permit repairs to the substructure of a bridge or pier.

Organization

Texas Historical Commission
The Texas Historical Commission sponsored the excavation of the La Salle shipwreck. For more information, call (512) 463-6100.

Books

Foster, William C., editor. "The La Salle Expedition to Texas: The Journal of Henri Joutel, 1684 - 1687." Austin: Texas State Historical Association, 1998.
Describes Henri Joutel's account of the historic journey with La Salle, written from detailed notes taken during the voyage.

Weddle, Robert S. "La Salle, the Mississippi, and the Gulf." College Station, Texas: Texas A&M University Press, 1987.
Provides several first-hand accounts by people affected by La Salle's voyage.

Article

Roberts, David. "Sieur de la Salle's Fateful Landfall." Smithsonian (April 1997): 41-52.
Presents La Salle's fateful journey to the Mississippi River and the recent excavation of La Belle.

Web Sites

NOVA Online - Voyage of Doom
http://www.pbs.org/nova/lasalle/
Includes an illustrated inventory of some of the more than 900,000 artifacts found on La Salle's ship La Belle, a look by underwater archeologist Toni Carrell at everything one can learn from the hull, and more. Note: Following the broadcast, the Texas Historical Commission will break the seals on a two-handled wooden box that has rested unopened in an aquarium in Texas ever since it was uncovered on the wreck on La Belle. Log on to find out the date and time.

Conservation Research Laboratory
http://nautarch.tamu.edu/napcrl.htm
Describes several nautical archeology projects the CRL is working on, including a conservation report on the La Salle shipwreck.

Texas Historical Commission La Salle Shipwreck Project
http://www.thc.state.tx.us/lasalle/lasbelle.html
Presents an online photo album of the excavation of La Belle, and the history of La Salle's exploration. Journeys, a online newsletter for teachers, offers activities, articles, and resources to help bring the life and times of La Salle to the classroom.

The "Build A Cofferdam" activity aligns with the following National Science Education Standards:

Grades 5-8

	Science Standard E: Science and Technology

Abilities of technological design

• Implement a proposed design. Students should organize materials and other resources, plan their work, make good use of group collaboration where appropriate, choose suitable tools and techniques, and work with appropriate measurement methods to ensure adequate accuracy.

Understandings about science and technology

• Science and technology are reciprocal. Technology is essential to science, because it provides instruments and techniques that enable observations of objects and phenomena that are otherwise unobservable due to factors such as quantity, distance, location, size, and speed. Technology also provides tools for investigations, inquiry, and analysis.

Grades 9-12

	Science Standard E: Science and Technology

Abilities of technological design

• Implement a proposed solution. A variety of skills can be needed in proposing a solution depending on the type of technology that is involved. The construction of artifacts can require the skills of cutting, shaping, treating, and joining common materials—such as wood, metal, plastics, and textiles.