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Note to the teacher: Students should have
calculators available for this activity.
Ask the class to brainstorm as to how many grasshoppers (or any other
choice of common insect) they think live in the school yard? Based on this discussion, each student
should make an estimate of the number he/she thinks there are.
Note to the teacher: If the school doesn't have a suitable yard, choose
some other location such as a nearby park. An entomologist determines an insect population by counting insects in
small samples, and then estimating how many insects there would be in the total area. In this task you will
play the role of an entomologist. Separate your class into groups of four or five students each. Each group
needs a plastic bag, pencil and
paper, and a hula hoop. Each group is to find a small open area in your
school yard. Each group tosses out a hula hoop in your area. This will be the boundary for your group's study
plot. Count all the grasshoppers that you find in the area and record. You may temporarily capture the
grasshoppers so repeat counting will not occur. Be sure to check under leaves, on top of the soil, in the
grass, on flower heads, and in the air.
When all groups are finished, release your captured grasshoppers.
Back in the classroom each group will report the number of grasshoppers
found in their area. In your small groups, discuss (a) why some plots have more insects than others, and
(b) what were some problems in trying to count all the insects. Estimate as accurately as possible the
area of the school yard and the area your class surveyed. Using these measures and your class' data, figure out
how many grasshoppers were in the whole field. Use percent of error to determine how good your
estimate was.
In your math or science journal, write a brief summary of this activity.
Explain the process of coming up with a population estimate.
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