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Investigative Case - "Holy Starbucks Batman!"

Developed for Lifelines Online by Stacey Kiser at Lane Community College. (http://bioquest.org/lifelines/index.html)

This material is replicated on a number of sites as part of the SERC Pedagogic Service Project


Students will investigate caffeine as a potential new pollutant in a northwest river system. Effects of caffeine on invertebrates and salmon fry will be explored through field work and lab work.

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Learning Goals

Students will be able to:
  • Describe how a pollutant moves through the hydrosphere.
  • Make measurements to assess water quality.
  • Identify field-collected invertebrates (at least to phylum).
  • Describe physiological differences and similarities across the invertebrate phyla in selected organism system/systems.
  • Summarize and report potential impacts of a new environmental pollutant (caffeine).

Context for Use

This case is appropriate for use in introductory environmental biology, introductory geoscience, introductory biology, and upper level courses such as ecology and zoology. This activity includes field work as well as lab work.

Considering Class Size - Different types of objectives can be accomplished by implementing case-based learning in different sized classes.

How Do Investigative Cases Fit into Courses? - What issues need to be taken into account before introducing cases to your class?

Teaching Materials


The DEQ reports that the Willamette River contains measurable levels of caffeine. Water samples were taken from Harrisburg, downstream from the Eugene water treatment plant and upstream from the city of Corvallis water intake facility. Data indicates the caffeine levels are increasing from year to year.

Local fishing groups are concerned about the potential impact upon food species for migrating salmon fry. "The caffeine may make them get to the sea faster, but if it kills their food sources then they are going to be awful hungry when they get there" stated an anonymous official.

Suggested Student Questions for Exploring the Case:
  • How does caffeine get into rivers?
  • What do salmon fry eat?
  • What types of salmon fry food species live in this part of the Willamette River?
  • What are the effects of caffeine on the food species? On the fry?
  • Should we do anything about caffeine in our river?
  • Have students fill out a table "What do you know?" vs. "What don't you know?"

Potential Activities to Use with the Case:
  • Collect and identify potential salmon fry food species in the Willamette River.
  • Potential link to chemistry: Measure caffeine levels in Willamette River from water samples (or in Lane CC sewage lagoons).
  • Study effects of caffeine on California Blackworm (Lumbriculus variegatus) and water flea (Daphnia spp).
  • Write preliminary report on the affects of caffeine on salmon fry food species to local city regulatory board.

Case Analysis Worksheet - A helpful aid in guiding students through the use of cases.

A map of the Willamette River Basin.

Teaching Notes and Tips

How To Use Investigative Cases with Examples - This area of the site lays out the phases Investigative Case Based Learning and key strategies for using it in your class.

Preparing Students for Cases and Collaborative Learning - Hints and advice on how to introduce cases into your class.


Assessing the Use of Investigative Cases - There are many informal opportunities to assess the performances of students who use investigative cases.

Suggested Student Products for use in Assessment of Learning
  • Field notebook from collection field trip, including identification of organisms.
  • Laboratory report on effects of caffeine on invertebrates.
  • Report to regulatory board with adequate research support.

Student Survey on Using the Case (Word 24 kB) Note: You may find it helpful to use this form to gather information from students if you wish to see how they view learning with cases.

References and Resources

Selected Web Resources:
  • 1995 Report on Mississippi River caffeine levels http://water.usgs.gov/pubs/circ1133/organic.html
  • Industry source: www.coffeescience.org/
  • Lumbriculus variegatus information and potential labs: http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/Lvgen4.htm
  • Daphnia information page: http://www.microscopy-uk.org.uk/mag/artmar02/fleanatomy.html#