BASIN Text Image
Current Theme: Learning
Macroinvertebrates Sampling (5th Grade Unit)

Fifth Grade Water Unit
by Kenneth Nova

Collecting Macroinvertebrates

For a more advanced version of this activity see the WatershED Learning Activity Assessing Your Waterway: Macroinvertebrates-Long Term Ecosystem Health

A terrific field activity for fifth graders, the following can be done in even the smallest of flowing streams or irrigation ditches.

Collecting macroinvertebrates from a stream is a fun and motivating activity for upper elementary school students. The quantity, types, and diversity of the "bugs" collected can reveal a lot about the health of a stream. Students will be surprised and amazed by the whole new world of life they uncover in this activity.

Samples can be collected in a variety of ways. A common technique is to place the net in the stream and then use a stick, your feet, or hands to stir gravel up-stream from the net. Macroinvertebrates will be dislodged and washed into the net. Empty the net into the specimen jar. For illustrations of this so-called "kicking and picking" see the following sites:


Another method is simply to collect a few submerged rocks, place them in a bucket and return to analyze the substrate back in the classroom. The bottom of the rocks can be scrubbed with a soft dishwashing brush to dislodge macroinvertebrates.  

Classroom analysis: Specimens can be classified using a variety of taxonomy guides. See the Izaak Walton League guide http://www.people.Virginia.EDU/~sos-iwla/Stream Study/StreamStudyHomePage/StreamStudy.HTML, which divides commonly found invertebrates into 3 classifications, depending upon the type of water quality they can tolerate.

For example: mayfly larvae are generally found in good quality water. Leeches may be found in all ranges of water quality, but you would not expect to find mayflies in water that has been severely polluted.

Have the students work in groups of 2-3 for classifying the bugs. They should also check for diversity of bugs. Have each group write up a summary of their results, evaluating what type of water quality they think exists, the diversity of organisms, etc.

Classifying water quality based on macroinvertebrates found is simply one more tool to complete the picture regarding the health of your stream. 

The following part of the activity might involve math that is too complex for some elementary school students. Calculators can facilitate the SCI computation.

Measuring Diversity: The Sequential Comparison Index

The diversity of organisms is also a potential indicator of stream quality. A simple diversity index, called the Sequential Comparison Index (SCI) can be performed by placing a random sample of invertebrates in a tray and counting the different organisms. Each time a different type of organism is encountered, the student will record this as the start of a new "run."

SCI = # of runs ÷ total # of organisms

The SCI runs from 0 to 1.0, with 1.0 representing the greatest diversity. You can use the SCI to evaluate water quality.

SCI Water Quality

0 - 0.30 poor

0.31 - 0.60 fair

0.61 - 1.0 good 

For example: You have collected 15 bugs. You identify a sequence of 5 mayflies (first run), and then find a leach (second run), then 4 mayflies, two scuds, a gilled snail, and then 2 more mayflies. Your number of runs is 6.

6 ÷ 15 = 0.40

The water quality is fair!!

The advantage of the SCI is you don't have to accurately identify all of the organisms, just whether or not they are different.

For a thorough and detailed description about doing stream macroinvertebrate survey, see 
This site includes illustrations of collecting samples in nets by "kicking and picking," as well as other information.


Pobst, Dick. Trout Stream Insects. 1990
Izaak Walton League. Save Our Streams Taxonomy Chart.

Ward, J.V. and B.C. Kondratieff. An Illustrated Guide to the Mountain Stream Insects of Colorado. 1992.


I would never recommend the following activity as a substitute for the field study of macroinvertebrates! However, if you have no access to a stream or irrigration ditch or if you need an idea for an activity which involves students using the internet, try the virtual macroinvertebrate activity at this site:

http://www.people.Virginia.EDU/~sos-iwla/Stream-Study/Samples/SampleIntro.HTML Return to BASIN Learning

Return to Fifth Grade Unit

INVITATION BASIN is a community project actively seeking public participation. We appreciate all feedback and welcome comments, suggestions and contributions. To find out more about how you can be involved, click here. Help BASIN serve your needs, take our "10 questions in 10 seconds" survey.

BASIN is supported by the US EPA, the City of Boulder, the Keep it Clean Partnership, BCWI and BCN

Home | Site Map | Glossary | Bibliography | Contributors
About BASIN | Attribution | Feedback | Search
Last Page Update - Tuesday December 27, 2005