How Much is There to Eat?


This activity uses simple math to compare the American South with India in terms of population density and food production.

Through this activity, students will:

  • practice practical math skills of estimation and calculation.
  • visualize relative sizes of areas and populations.
  • comprehend the relationship between population and food supply.
  • use comparisons and analogies for a clearer understanding of the real world in which they live.

The relationship between food production and population in a given area is demonstrated in this activity that compares India with the southern regions of the United States. The region of the United States below the 37th Parallel, from Arizona to North Carolina, plus Kansas and Missouri, is roughly equivalent to India in area and topography. Differences in weather and population density have a direct correlation with the amount of food that can be produced and the amount available proportionally to each individual.

Data given for the United States is from the U.S. Census Bureau. Population figures are from mid-1999. Data for India is from 2000 World Population Data Sheet, an excellent source of comparative data for living standards, population density, and projected growth figures (published annually by the Population Reference Bureau, Inc. and available online at

This activity provides students with a concrete example of the pressures that population places on food supplies and can be done as a simple math activity.(Note: All amounts have been rounded for easy calculation.)

  1. Make two columns on the board. Label one column INDIA, the other SOUTHERN USA. Divide each column into two parts, one for AREA and the other for POPULATION. Label one desk (or table half) INDIA, the other USA.
  2. Hand out scratch paper for use by students in doing calculations. Although this can be an exercise in practical math, the focus should remain on the comparison of the countries.
  3. Locate India on a globe or map (preferably on a globe so that its relative size and relationships with other regions are not distorted), and ask for area and population estimates. Record estimates on the board.
  4. Do the same for the combined area of the states below the 37th Parallel (Arizona, New Mexico, Texas, Oklahoma, Louisiana, Arkansas, Tennessee, North Carolina, Mississippi, Alabama, Georgia, South Carolina and Florida) plus Kansas and Missouri. Accept all guesses.
  5. Give the answers, or have students calculate the land areas using a 16" globe (on the surface of which 500 miles = 1 inch) and a flexible ruler. Have the students look up population figures in a recent world almanac or atlas and calculate the combined population of the states mentioned above.

    Answers: The area for each is approximately 1,150,000 sq.mi. Have the students round the area to the 100,000's place (1,200,000 square miles).
  6. Write the answer on the board under both India and USA.
  7. Record the population of India on the board (1,002,142,000 [2000]).
  8. Record the population of the southern US on the board (92,000,000 [2000]).
  9. Set out 24 rice cakes for each country on the labeled desks. Assume that one rice cake equals 50,000 square miles. Then, have students calculate the number of rice cakes needed to represent the Southern US or India? (1,200,000/50,000 = 24)
  10. While pointing out these regions of India on the globe or map, explain that:
    • The rugged, glaciated Himalayas make up 1/12 of India's landscape. Have students divide 24 by 1/12. (Remove 2 rice cakes from the India desk to illustrate this).
    • The Thar desert (in north western India) takes up another 1/12. Have students divide 24 by 1/12. (Remove 2 rice cakes to illustrate this).
    • The Southern Peninsula, approximately 1/3 of the land area, is plagued by monsoons, floods, droughts and tornadoes, and is an unpredictable producer of food. Divide 24 by 1/3. (Remove 8 rice cakes to illustrate this).
    • The remaining 1/3 of the land (represented by the 12 remaining rice cakes) is suitable for agriculture but also is home to the majority of the rapidly growing population.
  11. Point out to the students that these twelve rice cakes represent the amount of arable land capable of producing a dependable supply of food.
  12. While pointing out the following regions of the United States, have the students give what information they know about the climate and topography:

    • The dry high plateau of Arizona and New Mexico rises into the southern end of the Rocky Mountains, which represents 1/6 of the total area. Have students divide 24 by 1/6. (Remove 4 rice cakes from the USA desk to illustrate this).
    • Leveling out into dry grasslands in Texas and Oklahoma, 1/4 of the area. Divide 24 by 1/4. (Remove 6 rice cakes to illustrate this).
    • Further east and south are forests and hills (another 1/6). Divide 24 by 1/6. (Remove 4 rice cakes to illustrate this).
    • And low-lying wetlands (1/12). Divide 24 by 1/12. (Remove 2 rice cakes to illustrate this).
    • Leaving, like India, 1/3 for crop land. (The remaining 8 rice cakes represent this).
    • Compare the amounts.
  13. What about population? Ask the students:
    • If the population of this portion of the United States is approximately 92,000,000 (1999), and one student in this class were to represent 45,000,000 people, estimate how many students will represent the population of the southern USA. (Estimate: 90,000,000/45,000,000 = 2).
    • How many students for India's population of 1,002,142,000 (2000)? (Estimate: 1,000,000,000/45,000,000 = 22.2 = 22).
  14. Compare the amounts of food available per person in the U.S. and in India:
    U.S. has 8 rice cakes/2 people = 4 rice cakes per person. India has 12 rice cakes/22 people= about 1/5 rice cake per person.
  15. To make the comparison concrete, divide the students into India and the USA. Use a random method to choose two students to stand next to the USA desk and divide the rice cakes between them. The rest of the class probably won't fit around the India desk but can represent India's population from where they sit. Divide a few of the rice cakes in half.
  16. Explain that the people in India are currently able to live on the amount of food that is represented by this 1/2 rice cake. Ask what might be the problems if India's population gets bigger. Tell students that India currently exports food, and ask them to hypothesize on how this is possible.
  17. Compare the India amount with the U.S. amount. If people in India can live on one half of a rice cake, what does this mean for the people in the USA? What can be done with the extra food? (Export, which leads to higher per capita income, eat more, have enough food for larger families, use the surplus for manufacturing other products).

Please be sure to reinforce that this is just a comparison exercise and does not indicate either actual diet or actual amounts of food per person.

  1. Population, like interest on savings accounts, increases geometrically. Remind your students of the Rule of 70: anything increasing at the rate of 1% a year will double in 70 years (at the rate of 2%, in 35 years). See the Population Reference Bureau figures for current statistics for the world's countries (the 1995 rate of increase for the United States is 0.6%/year; the rate for India is 1.8%/year). Have the students calculate the projected populations for India and the southern U.S. region in 10, 20, and 30 years time. Have students determine how many people proportionally could be sharing the rice cakes in each country and hypothesize the potential effects upon India and the United States.
  2. Students can make three-way comparisons (which avoid "we-they" polarization) by using classroom or library reference materials to make the same rice cake calculations for the landscapes and populations of other comparably sized areas. Western Europe, like India, is on a peninsula, and with its varied languages makes a good comparison.

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