A Meal of Endurance

Lesson Objectives

By the end of this activity, students will be able to:
• understand the nutritional value of the explorers' meals.
• describe the trend in the diet changes that the explorers experienced over the two-year expedition and explain the physiological consequences that these changes implied.
• analyze caloric intake vs. caloric expenditure and recognize the pattern of slow starvation of the explorers.
• analyze the nutritional balance and caloric intake of the student's own diet.

Related National Standards

National Science Education Standards (National Research Council)
Science Standard C: Life Science
Regulation and behavior
• All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions while living in a constantly changing environment.
• Regulation of an organism's internal environment involves sensing the internal environment and changing physiological activities to keep conditions within the range required to survive.
Curriculum and Evaluation Standards for School Mathematics (National Council of Teachers of Mathematics)
Standard 7: Computation and Estimation

Tools and Materials Needed

• blue and red pen
• copy of Meals of Endurance activity sheet
• reference for calorie content of food

Estimated Time to Complete Lesson

The activity should take one class period to complete.

Teaching Strategy

Background information
The food Calorie (written with an upper case C) discussed in this guide and other nutritional references is in reality a kilocalorie, which is 1,000 calories. The daily amount of calories an individual requires is based on numerous factors. Chief among them are body build, height, gender, age, rate of metabolism, and level of activity. If an individual is in a very cold climate, he or she will need more calories to maintain body temperature. Due to these variations it is necessary to use calorie estimates when making comparisons of calories consumed versus calories expended.

It is estimated that at the beginning of the Shackleton journey (December 1914) the explorers had sufficient calories and a variety of foods to meet their nutritional needs at their level of activity. A year later—when they were stranded on the ice floes—the demands on them for physical labor increased and they probably expended more energy then they consumed. Also, the proportion of their diet that was comprised of carbohydrates was reduced (carbohydrates are essential for normal metabolic function). At the end of the journey—when the men basically had no carbohydrates left to eat—they had trouble performing physical labor. They subsisted on mainly seal, penguin, and seaweed.

A normal diet is approximately 35 percent fat, 10 percent protein, and 55 percent carbohydrates; the explorer's diet at the end was comprised just of protein and fat. At this point they neither consumed enough calories nor did they have the variety (carbohydrates and certain vitamins) in their diet necessary to fulfill basic nutritional needs.

Procedure

1. To help students understand what the Antarctic environment is like, have them read Danger on the Ice on this Web site.

2. Organize students into groups and distribute the Meals of Endurance activity sheet. Have students characterize the food listed on the sheet by placing a check in the appropriate food category (carbohydrate, protein and/or fat) and rate the meal as being satisfactory or not in terms of variety.

3. Have students calculate the calories the men consumed in the meal. Have students multiply this value times three in order to estimate the caloric intake of the men in one day. Have students evaluate the sufficiency of the caloric intake of the men in terms of calories expended in a typical day by the men. Students can make a bar graph where the vertical axis is Kcal and the horizontal axis is Time (December 1914 to May 1916). Have one column represent intake of calories and one column represent expenditure of calories. Do the men ever eat enough calories to sustain their activity levels? How would students describe the diet at the end of the expedition? Have students look at the three meals and discuss the trends in the variety and the caloric sufficiency of the diet the men consumed.

4. Have students keep a log of all the food they eat in one day. Then have them categorize it as they did the explorers' meals. Have them add in their own number of calories consumed to the bar chart. How does their diet compare with the explorers'? How might the energy required for a teenager living today's life compare with the calories required of an explorer?

5. To conclude the lesson, have students comment on the sufficiency and/or insufficiency of their own diet. Is a one-day analysis enough data on which to base a valid conclusion? What would students need to do in order to perform a more meaningful analysis of their diet? Have students discuss how important or unimportant food is in their day. Is variety important? How would they feel if they had no bread, fruit, or vegetables for a week? Ask students to imagine what it would be like to eat the restricted diet the explorers ate in a very cold and no-electricity environment for months on end.

Nutritional Analysis Tool
http://www.nat.uiuc.edu/
Provides an on-line program in which you can select certain foods and then ask for an analysis of the nutrients they contain. The results also gives the calorie contents for the foods chosen.
Unites States Department of Agriculture—Recommended Dietary Intakes (RDI)
http://www.nal.usda.gov/fnic/dga/rda.pdf
Gives the recommended daily intakes for infants, children, and males, and females above the ages of 11. (Requires Adobe Acrobat Reader software.)
Food Labeling Education
http://www.cfsan.fda.gov/~dms/foodlab.html

Assessment Recommendations

Students may be assessed through:
• their participation in the activity.
• the conclusions they draw about the changes they observed in the explorers diet.
• the accuracy of their own nutritional assay.
• the quality of their bar graph analysis of the calories consumed vs. the calories expended.

1. Research nutritional deficiency diseases such as scurvy or rickets. Were Shackleton and his crew in danger of suffering from either of these diseases? Are there areas in the world where deficiency diseases are still prevalent today?

2. Investigate the changes a body undergoes when it is starving. For example, female runners who traditionally have little body fat may stop menstruating. How may this be a survival strategy for the body? Another common response to starvation is that the body's metabolism slows down significantly. How is this helpful to survival?

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