Session 1
(45 minutes) 

Conduct this session in the classroom.

1. Show students
SOS: Save Our Streams (PowerPoint presentation). Stop throughout to discuss such concepts as:
 
• watershed
   
• definition of macroinvertebrate
   
• insect life cycles
   
• water pollution and its effect on different stream macroinvertebrates
   
• ability to determine water quality from a stream’s macroinvertebrate population.
 
2. Have students, working in pairs at computers with Internet access, go to
The Stream Study, and help them find the Web site’s Identification Key for common stream-bottom macroinvertebrates.
 
3. Hold up one of the enlarged pictures of a macroinvertebrate (unlabeled). Ask students to make observations about the organism. Then show the students how to use the key to identify the macroinvertebrate. Repeat with other macroinvertebrates as time allows, and share results.
    
4. Discuss the benefits of an identification key, including its function of narrowing one’s choices and eliminating the need to look at pictures of every organism.

Next: Session 2