SUBJECT: Math

OBJECTIVE: Students will study a yield map of a cornfield and learn many of the mathematical concepts used in its analysis. Younger students will color and count yield cells. Older students will average yield points within a cell and will be introduced to standard deviation.

MEASUREMENT: Students have seen and learned to read an actual corn yield map, and will have gained some insight into the math and technology being used by modern farmers.

BACKGROUND FOR TEACHERS:

Yield monitors are mounted in corn and other grain combines. They use sensors to measure the amount of corn as it is harvested, recording these values every 1-3 seconds. At the same time the amount of corn is being recorded, a GPS receiver is recording the exact field location. When those two pieces of information are combined, the amount of corn (usually reported in bushels) that was harvested can be mapped for every location in a field.

Farmers use yield maps to identify both good and poor-producing areas of their fields, and then try to take action accordingly. Low yields may be due to insects, diseases, poor fertility, a shortage or excess of water, and many other problems, which can be resolved through management.

Farmers also use GPS technology to apply varying rates of fertilizers and pesticides to specific areas of their field. They can target treatments to specific needs instead of treating entire fields. This has both economic and environmental benefits.

The components of a combine yield monitor can be studied at: http://www.deere.com/greenstar/gscombsystem.html.

STUDENT ACTIVITIES:

1. Ask students to read the story David Explores New Worlds, paying close attention to the paragraphs that describe the ways farmers use GPS. (".They could make maps showing where they planted different corn hybrids.and how much corn was produced in different parts of the field.then they could make better decisions.")

2. Click on this site: http://www.geofarm.com for a hands-on look at a yield map of a 58-acre cornfield (for information on acre measurements see Unit 1, Lesson 1). The aerial photo might give students a more realistic feel for the field-note the trees on the west, the farm building sites nearby, and the roads.

3. Students can follow the directions on-line, and answer the questions relating to the corn yield map. Or you can print copies. (Black and white copies will not work for yield maps, but can be used for the "cell" map. Younger students can color the map, either trying to match the real yields, or creating their own legends and "yields.")