6th Grade - Math

LESSON PROBLEM: Ratios and Percent: How has rice farming in Missouri changed over time? How can I express this in percentages?


Farmers in the United States have been growing rice for more than 300 years, beginning during Colonial times. Rice in the New World had its beginning in 1685. As the new nation of the United States started to grow, so did rice grow into an important crop.

Rice was the first commercial crop exported from the American colonies. By 1726, the port of Charleston was exporting about 4,500 metric tons of rice. When America gained independence 50 years later, rice had become one of its major agricultural businesses. Today, the rice producing states of Arkansas, California, Louisiana, Mississippi, Missouri and Texas together grow about 19 billion pounds of rice on 3 million acres and export about 6.4 billion pounds to 100 countries around the world.

The most recent state to grow rice is Missouri. The amount of land used for rice farming in Missouri was regulated and varied from 3,000 to 6,000 acres from the 1950's to the early '70's. These restrictions ended in 1974 and total rice acreage boomed to 14,000 acres. By 1988 Missouri had reached a record 128,000 acres. While Missouri is the smallest producer of rice in the U.S., by studying soil types and available water for irrigation, it has been determined that maximum rice cultivating land in Missouri can reach 300,000 acres. While rice acreage has increased over time, it is important to note that rice acreage is highly dependent on market prices, demand and supply. Market demand (a projection of how much rice will be sold)plus Supply (a projection of how much rice is available for sale) determines the market price (how much the farmer is paid for his crop) and guides the farmer in how much rice to plant in a given season. Rice yield (how much rice a farmer will harvest from each acre) is very dependent on growing conditions like the weather.

Reading about the history of rice production in Missouri is a fine way to learn and we can easily show what we've learned by using percentages.

Percentages tell us what part of a whole an amount is. "100" represents the whole. You know that if you get 100% on your quiz, you have gotten all of the questions right. So how many of the questions did you get right if you only got 50%? 50% is one half of 100, so you got half of the questions right. Let's write this out as a math problem: If there are a total of 20 quiz questions and you get 50% of them right, how many questions did you get right?
50% of 20 is N or .50 X 20 = N, N = 10
*keep in mind that "of" means "multiply" in math

Now let's apply what we've learned to our information on rice in Missouri. If the maximum land useable for rice cultivation will eventually be 300,000 acres. What percentage of total potential rice land was being used in 1998?

To solve this problem, let's first gather the information we need. What is the "whole" or value of the 100% we are dealing with? 300,000 acres. Right. What amount of the whole are we being asked about? The amount cultivated in 1998, or 128,000 acres.

Now let's form our question mathematically.
128,000 acre is what percentage of 300,000 acres?
N of 300,000 = 128,000

This is a little more tricky than the problem we did above, but I know you can do it. Instead of multiplying, we will divide to solve for N. Let's get N
by itself by dividing 128,000 by 300,000.
128,000 / 300,000 = .43 or 43%

Now that you have learned how to apply percentages to real life problems, think about other relationships in amounts of acreage farmed between the years 1950 and 1998 in Missouri.


Study the table at the bottom of this page that shows rice acreage farmed in Missouri from 1970 to 2000. Make up four percentage math problems based on this data.



Complete these percentage problems.

20% of 60 is _____

10% of 200 is ______

8% of 72 is ______

25 is _____% of 100

6 is _____% of 99

10 is _____% of 240


  • yields
  • percentage
  • acreage
  • data
  • allot

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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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