Keywords: biotic, abiotic, organisms, insects, graph, class, index; Grade Level of Lesson: 3-6 grade; Time Required: 2 hrs. (Can be done in two sessions); Setting: Local stream, classroom

Goals for Lesson

The students will be able to:

  1. Identify and name different aquatic insects
  2. Create a graphic representation of the number of different species of insects found (Plot and line graph, but a pictograph or bar graph could be used also)
  3. Determine the quality of the water in which the insects were found

Materials Needed

  1. 5 broom handles, nylon stockings, thick wire coat hanger
  2. 5 plastic trays
  3. Science notebooks for recording of findings
  4. Biotic index sheets for each student
  5. Magnifying lenses
  6. Graph paper
  7. Pencils and colored pencils
  8. Waders 5 pr. - one pair for each group

State Standards: Environment and Ecology - Watersheds and Wetlands 4.1.4 - A, C, E, Science and Tech. - Biological Sciences 3.3.4 A, Mathematics - Statistics and Data Analysis 2.7.3 C

Teaching Methods: Hands- on, Data collection and mathematical representation

Subjects Covered: Science, math

Topics Covered:

  1. Stream biotic index
  2. Graphing findings

Procedure: Review of Prior Knowledge

The teacher will ask the students: Other than fish etc. what creatures might you find in a stream? What are insects? What does biotic and abiotic mean? What is a graph?

  1. The teacher will tell the students that they will be doing a biotic index of a local stream and that they will then be graphing their results in the form of a plot and line graph. The teacher will then instruct the students on what a biotic index is and how it is used to determine the "health" of a stream, creek, or other body of water. The students will each be given a laminated copy of the Biotic Index Card . The class will discuss the information on the card and talk about how the three different classes of aquatic insects each represent a different stream "health". The teacher will ask:
  2. What are insects? What does biotic and abiotic mean? What can tell us the health of a stream? Etc….

  3. Students will be placed in groups of four for cooperative work. Each group will construct their own net out of a broom handle, nylon stocking, and a thick wire coat hanger (the teacher will lead and help each group in the construction of the nets). Before going out to the stream the teacher will tell the class the expectations and rules for being out of the classroom and in the stream.
  4. At the Stream: The student groups will each find a spot near the stream in which to set up their materials and conduct their insect and data collection. The teacher will demonstrate how to use the nets to catch the insects (walking slowly, pushing up stones with foot and allowing the insects to flow into the net etc.).
  5. One person from each group will be selected by each group to use the waders, enter the stream, and do the collection. The other three members of each group will have the trays ready and assist in pouring the insects in when they are obtained. After several scoops of insects, all people will come out of the water and begin to analyze their findings using magnifying lenses etc. Each person in each group will record the species and number of insect found (i.e. 10 Mayflies, 5 Caddisflies, etc.) the group members need to work cooperatively so that everyone comes up with the same information and numbers etc. When all insects are identified, counted, and recorded the students will dump the plastic trays of water and insects back into the stream. All items will be picked up and the group will make sure that they have all of their materials ready to return to the classroom.
  6. Back in the Classroom: Upon returning to the classroom the teacher and students will discuss their findings (kinds of insects found, numbers found and similarities of information between groups etc. They will also talk about the health of the stream and how it relates to the certain kinds of insects found. The teacher will demonstrate how to graph the information - selecting increments, labeling the X and Y axis, placing plots on graph paper etc.
  7. The students, in their groups of four, will construct their graphs. They will then write on the bottom of their graph paper, what their findings were as far as the health of the stream as it relates to their insect count/ graph.
  8. The teacher will lead a whole class discussion on the findings of each group and will answer any questions from the students. The teacher will ask:

How do insects help us to determine the health of a stream? What is a biotic index? How do graphs help us show our scientific findings? How could a graph be helpful when showing others our findings? Etc… The teacher and students will display their finished graphs and several biotic index cards in the hallway for other students to view.


  1. Participation in question and discussion sessions
  2. Recording of notes/ findings in science notebook
  3. Completion of group work - graph, analyzing data

Literature/ Sources

Biotic Index Card - William Sharpe, William Kimmel, Anthony Buda


Jeff Manley, Penns Valley Area School District (substitute)