Mini-Ocean Bathymetric Mapping Research Cruise

This activity is designed to take place near or at the end of a unit on the ocean floor. Students should be familiar with the physical features of the ocean floor including the continental shelf, abyssal plain, seamounts and guyots, seafloor ridges and trenches, and submarine canyons. The students should have also previously learned about sonar methods for mapping the ocean floor.

Objective

1. Students will create a mini-ocean floor with several specified features.

2. Students will make a bathymetric map of their ocean floor.

3. Students will make and carry out a plan to map an unknown ocean floor.

4. Students will use data collected to create a bathymetric map of an unknown ocean floor and then compare it to the actual topography.

5. Students will write a report of their activities.

Preparation

Day One:

The students will be given a large, empty, plastic container or bucket, such as a 3-gallon ice cream container or square 5-gallon bucket, and directed to build a model of an ocean floor.
Certain requirements and restrictions for the models will be given to the students, such as the ocean floor must cover the entire floor of the container and limitations on the overall height of the features (10 cm, for example). Provide the students will "props" such as Popsicle sticks, plastic spoons or forks, small cups or pieces of paper to aid them in the creation of their ocean floor. Other materials that have worked with this are clay, Styrofoam, wooden blocks and plastic cups. Be sure that the ocean floor is "submergible", i.e., firmly attached to the floor of the bucket, and that the containers can be fitted with a lid.

Each group will also create a 2D map of their ocean floor that indicates the location of features and the bathymetry.

The models will be set aside to dry and the lids need to be perforated with a coordinate grid. One method to achieve this is to mark out a grid on the lid and then to use a hot wire to melt holes into the lid at the marked intervals. Another is to cut out the center of the lid and replace it with hardware cloth. This will form the measurement grid for Day Three of the lesson. If the lid is not opaque, then water colored with food coloring or tempura paint will need to be used to cover the sea floor during the ocean cruise simulation. This adds an element of reality to the simulation!

Procedure

Days Two through Four encompass the research cruise simulation. The students will perform tasks as if they are planning and implementing a scientific research cruise including assigning tasks, creating a research plan, implementing the plan, dealing with unexpected delays and personnel or equipment issues while on a time schedule, analyzing their data and writing a cruise report.

Day Two:

There are two tasks for Day Two, Personnel Assignments and Creating the Research Plan. The students will work in groups of three to four and need to select jobs for the research cruise. They are given job descriptions for the following job assignments: Chief Scientist, Sounder Technician, and Recording/Plotting Technician. See student handout for descriptions of the jobs. Any groups with four students will have a Co-Chief Scientist.

After the students have negotiated their roles, they are given the logistics of the cruise in order to formulate a research plan. They have been given enough funding to take the research vessel to sea for a certain number of days (the length of class minus 10-15 minutes and then divided by 10). They can take a maximum of one reading OR move at most two grid positions every 30 seconds and each day is 10 minutes. It will take 5-10 minutes (1/2 to 1 day) to reach the research site.

If students do not complete a reading for technical reasons (equipment or personnel failure) they cannot make it up. They are also encouraged to repeat readings when possible to increase the accuracy.

At this point, the students type up a research plan proposal which includes their personnel and job assignments, a detailed mapping plan, a rationale for their plan, and a list of important factors that will need to be met to complete their plan. They also need to collect any equipment that they want to have "at sea", other than the measurement equipment provided by the teacher, and put it into a box or bucket designated by the teacher for that purpose. When they come to class the next day, they must have everything at their ship/table, since they will not be able to leave the ship/table once class has begun.

Day Three:

This is the day of the research expedition. The cruise begins at the start of class. The students are given ½ to 1 day (5-10 minutes) to prepare before they arrive "on station" and can begin mapping. Each group of students is given another group's model of the ocean floor to study.

If they are not prepared to begin mapping, then they will lose ship time and data (just like in the real world). Once students begin taking measurements they need to stay in their assigned roles. The Chief Scientist is responsible for watching the clock (the teacher assists with a timer and a "daily" announcement) and for keeping the group on-task during the cruise. He or she keeps the Daily Log, which records the location of the ship each "day", the time and location of each measurement along with the measurements themselves, and any deviations or changes to the research plan. He or she also ensures that all of the cruise documentation is completed and turned in on time.

The Sounder Technician is responsible for the sounding and measurement equipment (a blunt wooden skewer or thin dowel and a metric ruler) and for taking all of the measurements. The Recording/Plotting Technician records the soundings properly and creates the graphic representation of the ocean floor for the cruise report.

Each group could have one or two computers at their disposal depending upon technology resources that are available. While crews are "at sea," introduce occasional problems for the students to deal with, such as computer or equipment malfunctions, seasick personnel, stormy weather, etc. These will delay their readings and cause them to need to modify their plan. At no time does the ticking of the "day" clock stop, however.

Day Four:

After the cruise is complete, the crews will need to analyze their data, make conclusions and prepare a cruise report. Students focus on using the graphical representation of their data to identify the physical features of the ocean floor. Then make recommendations for research measurements that could be done on future research cruises. So students can have a sense of closure (which is unavailable to actual ocean scientists), they evaluate the accuracy of their map by comparing it to the actual ocean floor model. Lastly, students prepare a written cruise report that includes:

• Introduction –the purpose of the cruise;

• Personnel – who was assigned to the crew and their role;

• Initial Research Plan –the original plan;

• Modifications to Plan – list of changes that were made during the cruise;

• Results – graphical representations of the data;

• Analysis – identification of the ocean floor features;

• Conclusions – statements as to the accuracy of the map;

• Recommendations – suggestions for improvements, both for the crew's techniques and for the activity as a whole;

• Appendices – Daily Log, Table(s) of Data.

Assessment

The student work is assessed at four points:

• First, the ocean floor model is evaluated to ensure that groups adhered to the requirements for included features and scale. Each student also creates a paper map of their model identifying the features in their model.

• Second, the initial research proposal is reviewed for feasibility, the crew's justification of the plan and their ability to communicate ideas clearly.

• Third, on the day of the research cruise, student groups are informally observed for cooperative and collaborative behavior, their ability to solve problems that arise and that they work within the limitations set by the simulation (maximum number of readings per day, etc.)

• Lastly, the cruise report is evaluated for completeness, organization, clear communication, correct identification of ocean floor physical features, reasonable and thoughtful recommendations for improvements, and correct grammar, spelling and punctuation.

Credits

Misty Nikula