The Fish Kill Mystery: Using Case Studies in the Middle School Classroom
Heid, Christy, Biglan, Barbara, Ritson, Margaret, Science Scope
Case studies are an excellent method for engaging middle school students in the current work of scientists. Students learn to think like scientists as they decide how to investigate the dilemma presented in the case study. The National Science Education Standards' Content Standard for Science as Inquiry indicates that for the middle grades, understandings about scientific inquiry increase in complexity beyond those standards for the elementary grades (NRC 2000). Students in middle school should understand that scientific explanations emphasize evidence; have logical, consistent arguments; and use scientific principles, models, and theories. Through the case study, middle school students learn to use their skepticism to raise legitimate questions about scientific investigations and explanations.
One such case study, the Fish Kill Mystery, was of particular interest because it takes place at a popular vacation spot--the beaches of North Carolina. The original case came from the National Center for Case Study Teaching in Science at the University at Buffalo (Kosal 2003). We modified the case for use in the middle school classroom. The modifications included breaking the case into smaller "chunks" to fit in a 45-minute class period and creating recording sheets, as well as journal-entry and discussion stopping points. We designed a series of questions to follow each "chunk."
This activity became part of the existing curriculum unit on the environment and ecology. We do a unit that focuses on model rivers and how water has sculpted the land over thousands of years. It also focuses on the impact that humans and industries have on our water systems (George 1991), from toxic dumps to where dams should be built. The Fish Kill Mystery fits with the water systems unit.
Day 1: Introducing the case
The Fish Kill Mystery took place in the Pamlico estuary in North Carolina in the 1990s when billions of fish, predominantly Atlantic menhaden, were being killed in estuaries all along the eastern coast of the United States. We introduced the case study to students by reading its beginning section involving three young people who suddenly had their trip to the beach interrupted by the horrible stench of hundreds of dead fish. Students focused on the following questions to help them gather their thoughts on the Fish Kill Mystery:
* Where does this take place?
* What is the geography of this area?
* What were the volunteers at the cleanup doing?
* What sources of evidence could they gather at this site?
* What other sources of evidence do you think they should consider?
* At this time, what do you think killed the fish?
Once students had time to reflect on the questions individually, they worked in small groups of four to six to brainstorm which evidence, such as a reading of the amount of oxygen in the water, they should gather to determine why the fish died. Each small group used chart paper to display the five types of evidence they thought were most important. Their work was hung around the classroom and students participated in a silent "gallery walk" to read the other groups' proposed sources of evidence. (Depending on the time available and classroom dynamics, a student from the group that developed each poster could be posted at the display to answer viewers' questions.) After the gallery walk, students defended their choices, provided a rationale for their importance, and then the class, by consensus, chose the top seven sources of evidence for the class to focus on. Many students have pet fish and know how important it is to have aeration pumps bubbling oxygen in the water because fish are dependent on oxygen to survive. This led to the idea of testing oxygen levels in local water sources to determine typical dissolved oxygen levels in local bodies of water. Several students took containers home to collect water samples from local creeks, ponds, or rivers. …