UCMP Lessons  

Amazon Fly

Author: Judy Scotchmoor

Overview: This short activity quickly engages the participants in the process of science. They develop multiple hypotheses to explain a set of observations and figure out how to test these hypotheses.

Lesson Concepts:

Grade Span: 7 and up

Materials: none

Advance Preparation: none

Time: 10–15 minutes

Grouping: Appropriate for large group discussion

Teacher Background:

Scientists seldom follow a rigid scientific method. They do, however, ask questions based upon a set of observations. They then pose multiple hypotheses to answer that question. Each of these hypotheses are then tested and either retained or eliminated based upon the results of that test.

Vocabulary: hypothesis


  1. Relate the following story. (Only the names of the individual and the institution have been changed. The story is true.)
    Filbert Abercrombie was, and perhaps still is, a biologist from Oxford. His research was on the distribution of flora and fauna within the Amazon River Basin. The part that he loved most about his work was that he needed to spend months each year exploring and mapping some of the most remote parts of the Basin, following some of the smallest of tributaries. The remoteness of the area and the exploration really appealed to him, satisfying his sense of adventure and curiosity and at the same time giving him a certain sense of peace. There was only one thing that drove him up the wall...the masses of tiny flies that would forever pester him, getting into his eyes, nose and mouth. It drove him crazy!

    One day, Filbert was at his work and suddenly noticed that he was no longer swatting away at the pesky little flies. There were no flies around! He was, of course, delighted, but he also wondered why. He was really curious. So he sat down and looked around, looked at his notes, and tried to think of all the possible explanations for the lack of flies in this area.

    So let’s see what you come up with...

  2. Have the audience offer up possible hypotheses for why the flies were absent. Continue until you have a list of at least 10 or so.

    Great! Let's take a look at ...(select one of the hypotheses)... what could Filbert do to test this hypothesis?
  3. Following a discussion about their ideas, simply move on! They will want to know what the answer is. It is rather fun to make them wait until much later—even until the end of the day.

  4. Answer: At that particular site, the water level had risen so that plants that were normally above the water line were then submerged. The submerged leaves secreted a chemical into the water, which acted as a natural pesticide!

Updated November 31, 2003

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