Target Grade Level / Age Range:

4 th-5 th grade


1 hour


Students will practice math skills while becoming familiar with the uses of Iowa corn.


Suggested Companion Resources (books, websites, etc.)

  • Kernels of Corn History by Steve Kenkel and Loretta Sorensen (Local Authors)
  • Midwest Maize: How Corn Shaped the U.S. Heartland by Cynthia Clampit
  • The Story of Corn by Betty Fussell
  • Corn is Maize The Gift of the Indians by Aliki
  • From Kernel to Corncob by Ellen Weiss
  • Corn on and off the Cob by Allan Fowler
  • Corn up Close by Katie Franks


  • Carryover – the grain that remains unsold at the end of the crop year, and is held over until the next crop year to be sold.
  • Ethanol- Ethanol is made from the sugars in corn, blended with gasoline, and used for fuel.
  • Biodiesel – Biodiesel is made from the oils in soybeans.  It can be used alone or blended to make fuel.
  • Distillers grain-Distillers grain is a byproduct of ethanol.  It is high in protein and used in livestock feed.
  • Silage-Silage is chopped corn stalks or other grasses that is compacted and stored in air tight conditions and used as feed for cattle or sheep.
  • Ground feed-Ground feed is crushed corn, soybeans or other grains used to feed livestock.  
  • Exports-Exports are goods that are grown or made in the United States but sold overseas.
  • Imports-Imports are goods sold to the United States grown or made by people in another country.

Background – Agricultural Connections:

Corn is a very important Iowa crop! Iowa produces more of it than any other state. 99% of the corn grown in Iowa and across the U.S. is field corn. It’s not the kind we eat off the cob (that’s sweet corn), but is used for a whole variety of products instead. Field corn can be made into products using the whole kernel, such as taco shells or tortilla chips. But it can also be processed into corn syrup, which sweetens candy and fruit snacks or corn starch, which can be found in many products as a thickener – even laundry soap! Field corn is often used to make ethanol, which is mixed with gasoline to power cars. The by-products of ethanol (distillers grains and corn gluten) join field corn as a feed for livestock.

Interest Approach or Motivator:

Divide the students into teams with an even number of students and have them list as many uses of corn as they can in 5-7 minutes. Hand out the uses of corn paper and have them circle the uses listed that their group came up with. The team with the most uses circled is the winner.         


  1. Give each student four blank note cards. They should write “ethanol, 34%” “livestock feed, 36%,” “exports, 10%” and “food and industry, 9%” on the note cards.  Explain to students that they will be doing a hands-on math problem, but before they begin, they have to determine what livestock feed, exports, food and industry and ethanol have to do with corn. Give students 2-3 minutes to discuss this in their groups.
    1. Students should determine that these are the uses for corn. Have them write a short explanation of each category on the cards. For example:
      1. Exports – this is the corn that is sold to other countries. Many of the countries the US exports corn to, like China, cannot grow enough corn to meet their needs, so they import, or buy it and ship it in, from another country.
      2. Livestock feed – corn is an important ingredient in the feed for cattle, hogs, chickens and sheep. Some ethanol by-products are also used for livestock feed.
      3. Ethanol - a lot of corn goes into ethanol, a renewable energy that is mixed with gasoline to power cars. The ethanol processors don’t use the whole kernel, so many of the leftover products are used for livestock feed.
      4. Food and industry – this corn won’t be eaten off the cob, but field corn still has many uses in food and industry. It can be processed into tortilla chips and taco shells, used to sweeten candy and soda, and found in laundry detergents and sauces as a thickener.
  2. Have students count 100 kernels from a bucket of corn and put them in a Ziploc bag. Instruct them to keep their bag closed at all times, because every kernel is needed and none can get lost.
  3. Once each student has 100 kernels, instruct students to count out the percentages in corn kernels for each category. Paper plates are good for students to count in and contain any stray corn kernels.
    1. Students should recognize that because they have 100 kernels, each percentage should equal that number of kernels. For example, the ethanol category should have 34 kernels.
  4. Students will notice that there are 11 kernels left uncounted. Explain that those kernels represent carryover, or the grain from one year that is stored rather than used.
  5. Have students round each percent to the nearest tens place. For example, 34% should round to 30%, 36% should round to 40%.
    1. Have students represent the new percentages by moving kernels to the appropriate categories. Were there enough kernels? Why or why not? 
  6. Ask students to estimate an approximate fraction for each percentage without a calculator.
    1. Common answers could be ethanol’s 34%=1/3, livestock feed’s 36%=1/3, exports 10%=1/10, food and industry 9%=1/10, carryover 11%=1/10.
    2. Have students compare their fractions verbally with a partner using greater than, less than, and equals terminology.
  7. Have students add up their fractions using a common denominator. How does estimation affect the outcome of the problem?
  8. Review with students by having them remove two kernels from each category. Say a word or phrase and have students place a kernel in an appropriate category based on that word or phrase.
    1. Example words or phrases: renewable, processing, energy, chips, corn syrup, other countries, overseas.

Essential Files (maps, charts, pictures, or documents)

Extension Activities

  • Visit or Skype with a local corn producer to find out more about the path his grain takes once it leaves the field.
  • Visit or Skype with an elevator manager (Heartland Co-op, Key Co-op, etc.) to learn about grain is purchased and sold and tie to STEM.
  • Have students create a bar graph or pie chart to represent the uses of corn.
  • Have students select a use for corn and write a persuasive essay on why that use is the most important for daily life.



Yvonne Gaul - Kindergarten Shelby County Catholic School

Kelsey Faivre – Iowa Agriculture Literacy Foundation

National Agriculture Literacy Outcomes:

  • Plants and Animals for Food, Fiber & Energy Outcomes
    • Health: Identify examples of feed/food products eaten by animals and people
    • Identify renewable and nonrenewable energy sources
  • Culture, Society, Economy & Geography Outcomes
    • Social Studies: Identify plants and animals grown locally that are used for food, clothing, shelter and landscapes
    • Social Studies: Explain the value of agriculture and how it is important in daily life

Iowa Core Standards:

  • Mathematics:
    • 4.NBT.A.3 Use place value understanding to round multi–digit whole numbers to any place.
    • 4.NF.A.2 Compare two fractions with different numerators and different denominators, e.g., by creating common denominators or numerators, or by comparing to a benchmark fraction such as 1/2. Recognize that comparisons are valid only when the two fractions refer to the same whole. Record the results of comparisons with symbols >, =, or <, and justify the conclusions, e.g., by using a visual fraction model.
  • Social Studies:
    • SS.4.17. Create a geographic representation to illustrate how the natural resources in an area affect the decisions people make.
    • SS.4.26. Explain how Iowa’s agriculture has changed over time.
  • Science
    • 4-ESS3-1. Obtain and combine information to describe that energy and fuels are derived from natural resources and their uses affect the environment.
    • SS.5.13. Describe how goods and services are produced and distributed domestically and globally.

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