1. Build background.
Explain to students that of the seven species of sea turtles, six are endangered. One of the endangered species is the leatherback—the largest sea turtle. Adult leatherback sea turtles grow up to 2.4 meters (8 feet) long and can weigh 0.91 metric tons (1 ton). Leatherbacks migrate the farthest of all sea turtles, and dive the deepest. They have a soft, flexible shell that compresses, enabling them to reach depths of more than 1,219 meters (about 4,000 feet). There, they find their favorite food: jellyfish. Show students the photograph of a leatherback sea turtle on the National Geographic website, and have them read the Fast Facts.

2. Assign students sea turtles to track.
Assign each student an individual leatherback sea turtle to track on the Sea Turtle Conservancy website. Print out a map of each assigned sea turtle's route for students to refer to. Have each student analyze the route their assigned sea turtle swam in preparation for plotting it on the wall map of the world.

3. Have students complete the worksheet.
Give each student a copy of the worksheet Sea Turtles: Leatherback Sea Turtle Migration and have them fill in information about their turtles and their routes. Write the following formulas on the board for students to refer to:

• total number of miles ÷ number of days the migration took = average miles traveled per day
• average miles traveled per day ÷ 24 hours in a day = average swimming speed

4. Have students map the data.
Have each student plot his or her individual leatherback’s route on a large wall map of the world. Ask each student to use three thumbtacks to mark the beginning, middle, and end point of the route. Then have each student join his or her three thumbtacks with string.

5. Analyze the data.
Discuss the overall results. Ask:

• Which individual turtle traveled the farthest?
• Why do so many start their migration at the same place? (nesting beaches)
• Why do the routes differ so much? (currents)
• What problems might the turtles encounter along the way? (predators)

Extending the Learning

Leatherback turtles can stop blood flow to their flippers to preserve body heat in cold water. Have students do the following experiment: Take two latex gloves and tie off the fingers of one glove. Fill both with warm water, insert lab thermometers into the tops, and tie off the gloves around the thermometers. Immerse the gloves in a bucket of icy water. Have students record the temperature of the water in each glove every 6 minutes and create a line graph to compare how quickly each glove lost heat. Discuss how the glove with tied-off fingers had less exposed surface area from which heat could escape.