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5th Grade - Math
LESSON PROBLEM: Measurement: What units and concepts do we use to measure rice?
 STUDY GUIDE
Rice is measured in many ways: by the length (or size) of the rice plant or rice grain; by the area needed to grow rice crops; by the weight of how much rice is produced; and by the volume of rice harvested or the number of cups of rice we cook.
Because rice is an international commodity, rice measurements are expressed in two different systems -- the metric system and, for our purposes, the English system. Converting units of measurement from one system to the other is fairly easy using conversion tools.
In this example the U.S. system of measurements will be used, with the metric system measurements in parenthesis (metric).
Different types of rice are categorized according to the length of the rice grain compared to its width. The length (or size) of the rice grain or rice plant is measured in inches and feet (centimeters/meters). A mature rice plant can grow from a rice seed of a fraction of an inch to a rice plant of 24 inches (80 centimeters) to as much as 6 feet (2 meters) tall. Just like you grow from small to tall.
In the United States, more than 3 million acres of land are planted with rice. The area of a field planted with rice is measured in acres (hectares). From geometry we remember that area equals "length X width" and can be expressed in square feet. One acre is equivalent to 43,560 square feet. Historically, an acre was the amount of land a farmer could plow in one day's time using a team of oxen. The metric unit for an area planted with rice -- a hectare -- is almost as big as two football fields.
The package of rice we buy at the grocery store is measured by weight in ounces or pounds (grams). Or, for larger quantities, the weight is measured in hundredweights (metric tons), like the amount of rice that is produced, stored and sold as a commodity. More than 191 million hundredweights (cwt) of rice were produced in the United States in the year 2000. A hundredweight is equal to 100 pounds or 1/20 of a ton.
Volume, or the amount of space an object occupies, such as rice, can be measured in small amounts, by cups or quarts, or in large amounts, like bushels. A bushel is a dry measure (different from liquid measures) that equals 32 quarts. Millions of bushels of rice are harvested each year in the United States. In the rice industry, a bushel of rice equals 45 pounds.
Perhaps the most important measurement of rice for the rice farmer is yield. Yield is the total quantity of rice produced from cultivation. Yield is expressed usually as a ratio: how many pounds/tons per acre. For example, in California some farmers produce as much as 6,840,000 pounds of rice per acre.
No matter how you measure it, rice is a life-sustaining crop!
ACTIVITIES
Using a conversion table like the one below, convert these measurements from the U.S. system to the metric system or vice versa:
1. 1,442,000 hectares is _________________ acres.
2. 10 centimeters is ______________ feet.
3. 9,546,000 metric tons is _____________ U.S. tons.
4. 1 pint of rice is _____________ liters of rice.
5. 2 inches is ___________ centimeters.
| METRIC SYSTEM |
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| LENGTH |
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| Unit | Abbreviation | Number of
Meters | Approximate U.S. Equivalent | | kilometer | km | 1,000 | 0.62 mile | | hectometer | hm | 100 | 328.08 feet | | dekameter | dam | 10 | 32.81 feet | | meter | m | 1 | 39.37 inches | | decimeter | dm | 0.1 | 3.94 inches | | centimeter | cm | 0.01 | 0.39 inch | | millimeter | mm | 0.001 | 0.039 inch | | micrometer | µm | 0.000001 | 0.000039 inch | | AREA |
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| Unit | Abbreviation | Number of
Square Meters | Approximate U.S. Equivalent | | square kilometer | sq km or km2 | 1,000,000 | 0.3861 square miles | | hectare | ha | 10,000 | 2.47 acres | | are | a | 100 | 119.60 square yards | | square centimeter | sq cm or cm2 | 0.0001 | 0.155 square inch | | VOLUME |
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| Unit | Abbreviation | Number of
Cubic Meters | Approximate U.S. Equivalent | | cubic meter | m3 | 1 | 1.307 cubic yards | | cubic decimeter | dm3 | 0.001 | 61.023 cubic inches | | cubic centimeter | cu cm or
cm3 also cc | 0.000001 | 0.061 cubic inch | | CAPACITY |
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| Unit | Abbreviation | Number of
Liters | Approximate U.S. Equivalent | | | | cubic | dry | liquid | | kiloliter | kl | 1,000 | 1.31 cubic yards |
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| | hectoliter | hl | 100 | 3.53 cubic feet | 2.84 bushels |
| | dekaliter | dal | 10 | 0.35 cubic foot | 1.14 pecks | 2.64 gallons | | liter | l | 1 | 61.02 cubic inches | 0.908 quart | 1.057 quarts | | cubic decimeter | dm3 | 1 | 61.02 cubic inches | 0.908 quart | 1.057 quarts | | deciliter | dl | 0.10 | 6.1 cubic inches | 0.18 pint | 0.21 pint | | centiliter | cl | 0.01 | 0.61 cubic inch |
| 0.338 fluid ounce | | milliliter | ml | 0.001 | 0.061 cubic inch |
| 0.27 fluid dram | | microliter | µl | 0.000001 | 0.000061 cubic inch |
| 0.00027 fluid dram | | MASS AND WEIGHT |
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| Unit | Abbreviation | Number of
Grams | Approximate U.S. Equivalent | | metric ton | t | 1,000,000 | 1.102 short tons | | kilogram | kg | 1,000 | 2.2046 pounds | | hectogram | hg | 100 | 3.527 ounces | | dekagram | dag | 10 | 0.353 ounce | | gram | g | 1 | 0.035 ounce | | decigram | dg | 0.10 | 1.543 grains | | centigram | cg | 0.01 | 0.154 grain | | milligram | mg | 0.001 | 0.015 grain | | microgram | µg | 0.000001 | 0.000015 grain | Merriam Webster Dictionary
EXTENDED LEARNING
Make a chart of five U.S. food commodities, including rice (for example, wheat, corn). Then using the resource below and the World Wide Web, find out the United States figures for their yield. Rice: Yield and Production by Class, State, and United States, 1998-2000 | Class and State | Yield | Production | 1998 | 1999 | 2000 | 1998 | 1999 | 2000 | | | Long Grain | | | Pounds | Pounds | Pounds | 1,000 cwt | 1,000 cwt | 1,000 cwt | AR | 5,740 | 5,780 | 6,060 | 73,644 | 79,417 | 71,205 | CA | 5,570 | 6,800 | 7,100 | 537 | 340 | 355 | LA | 4,530 | 5,000 | 5,080 | 26,727 | 29,050 | 23,114 | MS | 5,800 | 5,650 | 5,900 | 15,544 | 18,250 | 12,862 | MO | 5,200 | 5,400 | 5,700 | 7,280 | 9,278 | 9,861 | TX | 5,610 | 5,920 | 6,740 | 15,598 | 14,978 | 14,087 | | | | | | | | | US | 5,426 | 5,587 | 5,680 | 139,328 | 191,863 | 131,484 | | | Medium Grain | AR | 6,200 | 6,230 | 6,300 | 12,400 | 15,513 | 14,679 | CA | 6,000 | 7,300 | 8,000 | 29,218 | 32,850 | 41,040 | LA | 4,500 | 5,070 | 5,150 | 1,380 | 775 | 1,288 | MO | 5,200 | 5,400 | 5,700 | 156 | 108 | 87 | TX | 5,000 | 4,900 | 5,800 | 250 | 294 | 255 | | | | | | | | | US | 6,616 | 6,811 | 7,377 | 43,404 | 50,540 | 57,319 | | | Short Grain | AR | 4,000 | 6,200 | 6,000 | 80 | 124 | 120 | CA | 5,060 | 7,000 | 7,300 | 1,531 | 3,500 | 2,190 | | | | | | | | | US | 5,185 | 6,969 | 7,219 | 1,711 | 3,634 | 2,310 | | | All | AR | 5,800 | 5,850 | 6,100 | 86,134 | 95,054 | 86,004 | CA | 6,850 | 7,270 | 7,950 | 31,386 | 36,090 | 42,585 | LA | 4,530 | 5,000 | 5,080 | 28,167 | 30,893 | 24,402 | MS | 5,800 | 5,650 | 5,900 | 15,544 | 18,260 | 12,802 | MO | 5,200 | 5,400 | 5,700 | 7,436 | 9,936 | 9,918 | TX | 5,600 | 5,900 | 6,700 | 15,846 | 15,272 | 14,342 | | | | | | | | | US | 5,663 | 5,866 | 6,278 | 184,443 | 206,027 | 191,113 |
VOCABULARY
- hectare
- acre
- ton
- metric
- volume
- ratio
- aggregate
- measurement
- commodity
- yield
Click here to play Rice Rampage!
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How is Rice Grown:
Farming rice is hard work. Click here to learn more about the Stages of Farming Rice. |
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