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Students will examine the growth, composition, history, and uses of corn through a close reading activity, discussion of renewable and non-renewable resources, and hands-on exploration of bioplastics made from corn.
Interest Approach – Engagement:
Activity 1: A Brief History of Corn
Activity 2: Renewable vs Nonrenewable Resources
Activity 3: Making Bioplastic
*These items are included in the Packing Peanuts Kit, which is available for purchase from agclassroomstore.com.
Corn Belt: the area of the United States where corn is the predominant crop grown
biodegradable: capable of being broken down through the actions of living organisms and natural processes over time
bioplastics: a group of plastics made from biological materials like plant starches, cellulose, oils, or protein
bushel: for corn, a unit of weight equal to 56 pounds
by-products: in agriculture, secondary products produced from the main product of a crop or animal; for example, cornstarch is a by-product of corn
compostable: capable of breaking down through the actions of living organisms in specific conditions to a defined outcome; generally, the conditions are moist, warm, and aerobic, and the end product is non-toxic compost that can enhance soil and support plant growth
endosperm: tissue formed within a seed that contains energy (starch) and protein for the germinating seed
germ: the living embryo of the corn kernel that contains the essential genetic information, enzymes, vitamins, and minerals for the kernel to grow into a corn plant
nonrenewable resources: limited natural resources that cannot be replaced or reproduced within a generation and cannot be managed for renewal. Examples: oil, soil, mineral resources (lead, iron, cobalt, zinc, etc.)
pericarp: the outer, protective covering of the corn kernel
recyclable: capable of being recycled
renewable resources: natural resources that can be replaced naturally or by human efforts at a sustainable rate. Examples: forests, fish, wildlife, agriculture, plants, animals
The Corn Belt is a region of the United States where corn is the predominant crop grown. Iowa and Illinois are the top corn-producing states, and they typically grow just over one-third of the US crop. Other major states for corn production include Nebraska, Minnesota, Indiana, Wisconsin, Michigan, South Dakota, Kansas, Missouri, Kentucky, and Ohio. These twelve states can be considered part of the Corn Belt. Warm, rainy summers and deep, fertile soils make this region particularly well suited for growing corn.
An ear of corn has an average of sixteen rows with 800 kernels. There are approximately 1300 kernels in one pound of corn. An acre (about the size of a football field) of corn can yield more than 13 million kernels. In the United States, corn production is commonly measured in bushels. This measurement originated as a unit of volume but has been standardized to units of weight for different commodities. One bushel of shelled corn is equivalent to 56 pounds (25 kg).
First domesticated in Mexico, corn is now grown on every continent of the world except Antarctica. The United States produces more corn than any other country. The scientific name for corn is Zea mays. All types of corn belong to this species, including sweet corn, popcorn, dent (field) corn, flour corn, and flint corn. Dent corn is the type most widely grown and processed in the United States. Hybrids of corn, produced by crossbreeding different varieties, have been developed to grow well in varying conditions and locations worldwide. The development of hybrid varieties, along with synthetic fertilizers and new farm machinery, has facilitated huge increases in corn productivity. Today, more corn can be grown on less land than ever before.
Similarly, advances in technology allow us to use more components of the processed corn kernel than ever before. One hundred years ago, starch was the main product used from refined corn, while the rest of the kernel was thrown away. Today, there are uses for every part of the kernel—even the water in which it is processed. The corn seed (kernel) is composed of four main parts: the endosperm, the pericarp, the germ, and the tip cap. The endosperm makes up most of the dry weight of the kernel and provides the source of energy for the seed. The pericarp is the hard, outer coat that protects the kernel both before and after planting. The germ is the living embryo of the corn kernel. It contains genetic information, vitamins, and minerals that the kernel needs to grow. The tip cap is where the kernel is attached to the cob and is the major entry path into the kernel for water and nutrients.
Corn is a versatile crop. It is the major grain grown for livestock feed by farmers in the United States, leading all other feed crops in value and volume of production. Corn is a major component in foods like cereals, peanut butter, and snack foods, and it is also processed into a wide range of industrial products, including ethanol. The kernel is used as oil, bran, starch, glutamates, animal feed, and solvents. The silk is combined with other parts of the corn plant to be used as part of animal feed, silage, and fuels. Husks are made into dolls and used as filling materials. The stalk is used to make paper, wallboard, silage, syrup, and rayon (artificial silk).
Corn can also be used to make a type of plastic known as bioplastic. Commonly, plastic is made from petroleum, a fossil fuel that is a nonrenewable resource. In contrast, bioplastic is made from biological materials—plant starches, cellulose, oils, or proteins. Unlike petroleum-based plastics, bioplastics are made from renewable resources such as corn, potatoes, tapioca, and casein (milk protein). One example of a bioplastic application is packing peanuts—the loose fill that goes all over when you open a package. Some packing peanuts are made of polystyrene (Styrofoam), which is a petroleum-based plastic. Corn-based packing peanuts are made of over 99% cornstarch and a very small percentage of food-grade oil. These packing peanuts are non-toxic, biodegradable, and compostable.
It is important to note that there are pros and cons to both bioplastics and petroleum-based plastics. There are also some common misconceptions about the differences between these groups of plastics. For example, both bioplastics and petroleum-based plastics can be biodegradable, meaning that over time they break down into compounds like carbon dioxide, water, and methane when exposed to naturally occurring microorganisms like bacteria, fungi, and algae.1 Also, some bioplastics are recyclable.1 The ability of a plastic to be recycled or to biodegrade depends on the chemical structure of the plastic, not whether the plastic is made from renewable or nonrenewable materials. In addition, many people are unaware that the raw materials used to make petroleum-based plastics are the by-products of refining crude oil for fuel. If these by-products were not used to make plastics, they would be industrial waste that would need to be disposed of. For more information, see the segment from D News, The Truth About Biodegradable Plastic.
|Aspirin – cornstarch||Baking Powder – cornstarch|
|Batteries – cornstarch (insulation)||Bubble Gum – corn syrup|
|Coke – corn syrup||Corn Tortillas – corn flour|
|Crayons – corn oil||Crunch Berries – corn syrup|
|Diaper – cornstarch||Gain Detergent – cornstarch|
|Matches – cornstarch (match head)||Pasta – does not contain corn|
|Shoelaces – cornstarch (for smooth tying)||Snickers Bar – corn syrup|
Activity 1: A Brief History of Corn
Activity 2: Renewable vs. Nonrenewable Resources
Activity 3: Making Bioplastic
Concept Elaboration and Evaluation
Refer to the information found in the Background Agricultural Connections section of the lesson to help guide this discussion. Be sure students recognize that while corn plastic is made from a renewable resource, there are still pros and cons to its use. Point out to students that scientists will be needed to help discover new and improved solutions to challenges surrounding the use of natural resources, the best methods of recycling, and the reduction of waste in our landfills and oceans.
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Watch the 3-minute "How Stuff Works" video clip about Corn Plastic.
Learn more about how petroleum-based plastic is made and recycled by watching the video From Oil to Plastic.
Make corn Johnnycakes in your classroom. The batter is simple to prepare and cooks quickly on an electric griddle.
Read Issue 5 of Ag Today titled Agriculture in Society. This reader can be printed or accessed digitally. Students will learn the term sustainability and what that means to farmers who need to produce 60% more food with the same amount of land in order to feed a growing world population. Learn what byproducts are and how they are used, how food packaging has decreased waste, and how farmers use technology such as various tools, robots, and hand-held devices to improve their efficiency.
Play the My American Farm interactive game Amazing Grains.
View the video Farm to Car to explore how plant-based plastics are being used in the automotive industry.
The bioplastic or corn plastic activity has been part of numerous presentations and published informally by several Agriculture in the Classroom programs and agricultural science programs. The original source for the bioplastic mixture is unknown.
Lynn Wallin, Lyndi Perry, Debra Spielmaker, Jessica Budge
Oregon, Utah, and Illinois Agriculture in the Classroom