Rice-a-rithmetic

Grade Level:
4, 5, 6, 7, 8

Time Required:
50 minutes per day for two days (or one day and a homework assignment)

Objectives/Goals:
1. Students will learn facts about rice as an agricultural crop and wildlife food.
2. Students will be able to perform sampling methods and estimating techniques.
3. Students will know weight conversions for ounces, pounds, and tons.
4. Students will be able to complete simple multiplication word problems.

Curricular Areas:
Listening, following oral and written instructions, collecting and analyzing data, problem-solving, mathematical reasoning.

Overview:
1. A teacher lecture introduces concepts and vocabulary.
2. Student groups survey simulated rice fields for food availability.
3. Each student will complete a Rice Food Production Study Worksheet.

Lesson's Concepts:
1. Rice has historically been a staple food and is a major crop produced in California.
2. Rice lands provide valuable year-round habitat for waterfowl and other wildlife.
3. Waterfowl help farmers reduce pollution, decompose rice straw, and fertilize fields.

Materials Needed:

• uncooked brown rice grains (1 pound for 30 students)
• blank copy paper (2 sheets for every four students)
• Rice Food Production Study Worksheets
• pencils
• calculators (optional)

Part One: Rice Field Surveying
Preparation:
1. Purchase uncooked brown rice at a local grocery store, either prepackaged or from the bulk food section. For 30 students, you will need about 1 pound of rice.
2. On a blank sheet of copy paper, create a grain grid by drawing nine equal boxes, as shown here. The grid should fill the page:

3. Make a grain grid for each group of four students.
4. Clear a space for each group either on a level table or on the uncarpeted floor.
5. Read through the teacher lecture. For more information about California rice farming visit www.calrice.org.

Procedure:
1. Gather the students together. Discuss rice farming and how rice is grown, using the information provided in the teacher lecture.
2. Review the activity objectives and vocabulary. Write vocabulary words on the board.
3. Divide the students into groups of four. Assign each group a hard-surface work area.
4. Give each group a blank sheet of copy paper and a paper marked with a grain grid. Explain that the grid represents a section of a harvested rice field. The students will be sampling four of the squares on the grid to determine the amount of grain left behind after harvest. This grain would be available to hungry waterfowl and other wildlife.
5. Have each group randomly select four squares withing their grain grid (each square equals one square foot). Mark the selected squares 1, 2, 3, and 4 (it's okay to write in the squares).
6. Have one student in each group take a handful of brown rice and carefully but randomly scatter it across the entire grid. Don't worry if some of the grains fall outside of the grid; leave them wherever they fall.
7. Have each student in the group take one of the four numbered squares and count every rice grain in the square (do not count grains that rest on a grid line). Record the total for each of the squares (1 through 4) on the blank sheet of paper. To analyze the samples, have each group perform the following calculations:

(a) Calculate a total grain count (add all four counts together).
(b) Average the total grain count (divide the total by four).
(c) Determine the average number of grains per acre for the simulated rice field.
Hint: 43,560 square feet = 1 acre. (Multiply the average of the samples by 43,560)
(d) Estimate the total amount of grain in the grain grid by visually comparing the counted squares to the uncounted squares.
(e) Calculate the average for the estimates (divide the total estimate by 9).
(f) Determine the average number of grains per acre using the estimate (multiply the average for the estimates by 43,560)
(g) Count all the grains in the grain grid to determine the true total.
8. Discussion: Explain that scientists use a variety of methods for evaluating wildlife habitat. Sampling entails testing several small areas and applying the results to the entire field, as was done by counting four squares, averaging them, and applying that to an entire field (problems a-c). Estimating entails using a known quantity to visually evaluate a larger area, as was done when students visually compared counted squares to uncounted ones (problems d-f).

• Ask each group which method was closer to their actual total?
• Was the same method most accurate for all groups?
• Would it be possible to count an entire acre instead of sampling or estimating?

9. Direct students to clean up their work area, collecting and disposing of the used rice grains.

Part Two: Calculating Food Availability
Preparation:
1. Make a copy of the Rice Food Production Study Worksheet for each student. To increase difficulty for more advanced students, do not provide the equations on the worksheet.

Procedure:
1. Gather the group together to share the objectives of the day. Using the teacher lecture, discuss the mutually beneficial relationship between waterfowl and rice farmers.
2. Pass out the Rice Food Production Study worksheets and calculators (optional). Discuss the information given at the top of the worksheet, and review unit conversions if necessary (ounces to pounds, pounds to tons). Point out the hints given for questions 1, 2, 4, and 5.
3. Allow students to get started, or assign the worksheet as homework.

Assessment:
1. Answers to the worksheet are provided in the Answers Section below. Points, grades, or percentages may be assigned to each student's worksheet.
2. A portion of the score may also be given for listening and following directions. If worksheets are completed in groups, cooperative table work may be considered in assessment.

Follow-up/Extensions:
1. Use sampling to determine the number and type of plants growing in a natural area of the school campus. Have students mark off a one foot square area, sketch the various types of plants growing in the sample area, and count how many of each type of plant is present. This can be done either by pulling/digging up all of the plants in the sample area and sorting them or by using a string during the counting process to separate the counted from the uncounted area.

Students can make a table to record and clearly present their data. Also have them chart the quantity of each plant found and calculate the percentage of each plant present. For an additional challenge, have the students use a plant guide to identify at least one of the plants found in the test area.

2. Visit a rice field just before or during harvest in the fall (August to October in the Sacramento Valley) to see the shallowly flooded plants with full seed heads. Observe the field and make journal notes of any wildlife that are present. Return to the same field in December to see what type of method was used for rice straw removal or decomposition (burning, flooding, harvesting straw for fuel or insulation, etc.). Again make journal notes of any wildlife that are present.

3. Hold a rice harvest celebration in class. Have students prepare and bring a variety of rice dishes: soups, salads, breads, main dishes-and even desserts. Recipes are available online at sites such as www.calrice.org, www.ricecafe.com, www.recipesource.com/fgv/rice/, and www.successrice.com/recipes.shtml.

Vocabulary List:
acre, amphibian, beneficial, consumptive, decompose, estimate, gallon, habitat, ounce, paddies, pollution, reptile, rice straw, sample, staple, ton, waterfowl, wetland

Teacher Lecture:
Rice is the staple food for two-thirds of the world's population. Rice is believed to have been grown in Asia as early as 5000 B.C. Rice was first planted in California during the Gold Rush. Today, about 500,000 acres of rice are planted each year in California.

A rice plant is a type of grass, and the rice grain is actually the fruit of the flowering rice plant. Rice is grown in water_filled fields called paddies. Although rice does not require complete flooding to grow, it does best when it is submerged in about two to three inches of water. Flooding rice fields helps prevent weeds, reduce insect pests, and regulate the temperature of the field to keep the crop cooler on hot days and warmer on cold nights. Many people think that rice is a highly water-consumptive crop when, in fact, quite the opposite is true. One serving of rice requires 25 gallons of water to grow. Compare that to beef, which needs 1,231 gallons per serving, and chicken, which needs 330 gallons per serving. Almonds need 80 gallons per serving, and one serving of cantaloupe requires 40 gallons.

Rice production in California provides something very critical to the conservation of our natural resources. Agricultural wetlands created by rice farming provide important habitat for the millions of waterfowl and shorebirds that visit the Central Valley every year. Rice fields are important during the spring and summer when ducklings, amphibians, reptiles, and many other animals find food and shelter among the growing plants.

When the rice is harvested in the fall some rice and about three tons of rice straw are left behind on each acre of rice field. The rice straw has to be removed before the next crop of rice is planted. For many years the straw was burned to control plant diseases, but the smoke polluted the air. Now many farmers flood their fields during the winter, and the water helps break down the straw. Waterfowl walk through the fields looking for the leftover rice grain. As they do they trample the rice straw and help it decompose. This mutually beneficial relationship helps everyone; the waterfowl gain critical habitat and food, the farmers are able to reduce burning and air pollution, and the citizens of the Central Valley are able to see and appreciate the wonderful array of waterfowl that visit each year.

Handouts/Visual Aids:
1. Rice Food Production Study Worksheet

Answers:
Following is the answer list for the Rice Food Production Study Worksheet:

1. 16 oz/pound X 300 pounds/acre = 4,800 oz/pound

2. 2000 pounds/ton X 3 tons/acre = 6000 pounds/acre

3. 300 pounds/acre X 200 acres = 60,000 pounds of rice 60,000 pounds of rice X 16 oz/pound = 960,000 oz of rice

4. 4 oz X 120 days = 480 oz of rice that one duck would eat during the winter season

5. Part 1: 500 acres X 300 pounds/acre X 16 oz/pound = 2,400,000 oz of rice
Part 2: 2,400,000 oz of rice ÷ 480 oz of rice/duck = 5,000 total ducks fed

Credits:
Text Adapted from U.S. Rice Producers Association: http://www.riceromp.com.
Activity Adapted from Earth Stewards - Sacramento National Wildlife Refuge