6th Grade - Math

LESSON PROBLEM: Estimation: What is the connection between rice and estimation?


Did you know the most widely used grain in the world is rice?

Based on everything you know about rice what is your best guess as to where most of the rice eaten in the United States is grown? An educated guess is an estimate.

Did you guess a continent? A country? Did you guess the United States? You are right! More than 90 percent of the rice consumed in the United States is grown by U.S. farmers.

How did you guess? Did you think about rainfall, landforms, and cultural eating preferences? You can estimate, based on your prior knowledge and current information.

An important tool for estimating is rounding off numbers. When you say someone has about a dollar, you are rounding off to the nearest dollar. You do not know exactly how much he has. He may have 96, 97, 98 or 99 cents.

You know the rule for rounding off. Let's review the rule. If the number is 1,2,3, or 4, change the numbers to a zero. So, 91, 92, 93, or 94 cents is closer to 90 cents. If the number is 5, 6, 7, 8, or 9, go up one number to round it off. So, 98 cents is about one dollar.

Try some estimating problems.

If 90 percent of the rice eaten in the U.S. is produced in the U.S., what is the percentage of rice eaten that is produced by other countries?

If Americans eat 27 pounds of rice (uncooked) per person each year, how much of that rice comes from the United States? Can you estimate? If the U.S. accounts for about 90 percent of the rice eaten in the country, then what is about 90 percent of 27 pounds? Can you estimate 50 percent?

Let's make it challenging by adding formulas.

First estimate, then use the formula for proportions. A/B=C/D

A = number of countries B = tons of rice C = % of Asia and D = % remaining. Now plug in the numbers. Did it agree with your estimate?

The formula for a rectangle is Area=Length x Width or Base x Height. So, if a rice farmer in Louisiana needs to cover three fields that are 5 miles wide by 20 miles long, what is the area covered? What is your answer?

Do you recall what a ratio is? A fraction! Use this formula. One number is compared to another, such as, 3:5. Can you change a ratio into a fraction?
3:5= 3/5.

If the U.S. exported 250,000 metric tons of rice in 1996, and 350,000 metric tons in 2000, what is the percent increase? So, plug in your new numbers and the answer will become a percent. Did you divide the bottom into the top? Did you have to place a decimal point and add two zeros?

Did you get 49 percent increase?

Remember this: If the numbers are both in acres, then you are ready to do the arithmetic. If not, you have to change them. For example, if one number was given in square feet and the other in acres, you would need to change the numbers to the same unit, before proceeding.

Use the formula for Distance : Distance = Speed or Rate x Time. Two California rice farmers had to seed their rice fields using an airplane. The airplane travels 60 miles per hour and it takes about 2 hours, so what distance can the airplane cover? How many miles is that? Did you get 120 miles? Can you change that into meters?


How well do you estimate?

Can you estimate how long a pier is on a lake?

Do you estimate how high a plane is in the air?

Have you estimated how far away lightening is from you by listening to the thunder?

You will find many ways to estimate a solution to word problems.

Enjoy yourself !

Go to the Internet or a library and find a book about rice. Look in the back of the book or on the Internet for a glossary about rice.

You can find at least two pages of different parts of rice and how they are used.

Make a chart having two parts: Food or Edibles and Non-Edible Food. For example, cereal comes from Rice Bran however, broken kernels are used in pet foods.

Make a list using different colors for each side. You might choose the yellows, oranges, and red shades for Edible foods and the green, blue, and purple shades for Non-edible foods or vice-versa.

Or, design your own chart.


Compare the rice production in the USA to the other countries in the world. Go to: Riceweb.org/geography.htm.

Make a map of the world showing the continents. Color the continents using a key at the bottom to show the millions of tons that a continent produces.

Make an additional chart to show the 30 countries where rice is produced. Click on any country to find out some interesting facts.

List one fact for each country. Share it with your classmates or family. Know more about rice than your friends.


  • estimation
  • proportions
  • continent
  • stimulating

Click here to play Rice Rampage!
The Milling Process for Rice:
Getting rice from the field to you takes
a few more steps. Click here to see a video & learn more about the rice milling process.
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