In today's lesson, students will learn about pollution-tolerant macroinvertebrates. Because many of these macroinvertebrates are not insects, I begin this lesson by reviewing the Characteristics of Insects and the Insect or Not Reflection Sheet that students completed in lesson two of this unit. Students may need to review the key vocabulary from this lesson as well.
In this lesson, students will continue to work on their macroinvertebrate idenitfication charts that they started when they learned about pollution-sensitive macroinvertebrates.
As in the previous lesson, I use the macroinvertebrate indentification presentation to show students an example of each macroinvertebrate species and to discuss its features. I model the correct completion of the chart on the board so that students can copy the pertinent information and encourage them to add their own observations. After introducing each species, I stop and refer back to the insect characteristics and guide students to determine whether or not each pollution-sensitive macroinvertebrate is an insect or not. Please see the student sample of a completed chart to see a typical student's work.
Unlike the pollution-sensitive macroinvertebrates the students learned about in the prior lesson, the presence or absence of these macroinvertebrates in the stream ecosystem may not tell us much about water quality. Pollution-tolerant macroinvertebrates can live in polluted water, but are also often found in healthy streams. When introducing these macroinvertebrates to students, I make sure to note that finding some of these macroinvertebrates in the water does not indicate poor water quality unless we find only these macroinvertebrates and no pollution-sensitive species.