Water Quality - http://www.webrangers.us/activities/waterquality/ - In this online interactive, learners explore the various types of life that live in fresh water systems and how the presence of these organisms is an indication of the overall health of the water. Learners perform a water quality test that simulates tests performed in the field and use the data to determine the pollution level of three different streams. This activity also introduces learners to macroinvertebrates (animals without backbones).
Collecting Invertebrates to Determine Water Quality - http://pbskids.org/dragonflytv/web_assets/pdf/dftv_gpsedguide_alligatorhabitat.pdf - This activity (located on page 3 of the PDF) is a full inquiry investigation into organisms and the health of their ecosystems. Groups of learners will net and count different types of invertebrates from a local pond, lake, or stream, then group them by their tolerance to pollution and make calculations to determine the quality of the water. Relates to linked video, DragonflyTV GPS: Alligator Habitat.