Thursday, September 24, 2009

Stonefly Lab at White Swan

Students were introduced to the phylum arthropoda this week with Hesperoperla pacifica as the beast of the week. Following a brief introduction that included their habitat of cold, highly oxygenated streams and rivers, role in the ecosystem and salmon recovery and their sensitivity to contaminants and increases in water temperature making them an indicator of environmental health, students were allowed to observe the stonefly larvae doing "push-ups". Rather than explaining the behavior is related to respiration by increasing water flow to external gills, students were encouraged to develop a hypothesis and chose something to change from a brainstormed list of environmental factors (light, number of stoneflies, aeration, temperature and depth of water) in order to observe changes in push-up rate. The following day students were given an explanation of manipulated and response variables and then allowed to design a controlled experiment in order to collect data to test their (old or new) hypothesis.

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