Several years ago I attended a workshop on using the Stella II modeling program in Advanced Placement (AP) Environmental Science classes. My initial reaction was "Wow! What a powerful tool to integrate into, say, a population analysis for the class." My second reaction was "When would I get the time to learn how to set up, and master, the program to conduct such an analysis?" Not being very computer literate, and like many of my colleagues who are stretched to the limit with regard to the time that the day to day teaching workload demands, it became one of those projects that went into the "to do" pile on my desk!

Imagine my next reaction, when I was informed about the newly developed Food Chain interactive CD-ROM that utilizes a systems approach to analyze a simple lake ecosystem. The background tools needed to conduct the investigation had already been set up on the disc for students to explore in the classroom. I did not have to figure out that side of things, but simply could put the disc into the drive and get my students to embark on the journey of "structured discovery" for themselves! This is exactly the kind of material that teacher's need, which takes a minimal amount of set up time, is described in an easy to understand manner for both teacher and student, and provides the class with a very worthwhile activity.

The students have the concept of the interconnectedness of natural systems reinforced through the Food Chain program that enhances critical thinking, problem solving, and analytical skills, through a series of enjoyable challenges that the students conduct. This could be to determine which two species could survive in the lake by themselves for a period or time, or what are the minimum requirements to keep a sunfish alive. Students have to produce hypotheses and design experiments along the way, as well as analyze graphs and data relating to, for example, the levels of oxygen and carbon dioxide in the lake. For teachers who wish to take a systems approach to the next level with their students, another section of the program called "Generalizing" provides that opportunity.

I used Food Chain over three-class periods as an introduction to ecosystems with the students in my AP Environmental Science course. In keeping with the "learning through discovery" approach that the program offers, I kept the teacher induction to a minimum and allowed the students, working in pairs, to learn by deduction as they moved through the challenges presented in the program. Although the lake ecosystem described in Food Chain is simple, it does a very good job of reinforcing the basic requirements of any type of aquatic or terrestrial ecosystem; namely the need for producers, consumers, and decomposers. After each of the student challenges, I facilitated a discussion on what the students had ascertained so far. Common themes emerged, and explanations as to which experiments worked, and which did not, ensued, providing for a lively interaction among the students. By using the Food Chain program, they were exposed to an enjoyable learning strategy that enabled them to experiment with variables, observe the results of their manipulations graphically, and ponder the answers to a number of important questions as to how ecosystems function. More importantly, they had developed ownership for what they had learned in the process, which is far better than if I had stood in front of them and lectured about the workings of a lake ecosystem! The students were far more receptive to follow-on activities, such as adding more species and producing a food web, or assessing the consequence of introducing a foreign species into an already fully functioning ecosystem.

There are many opportunities to use a systems analysis approach when studying the environment, although few textbooks, or other media, refer to systems thinking strategies as a way of engaging students. Food Chain is a welcomed addition to my classroom resources, and will be for years to come. It uses a pedagogical approach that I believe in, and gets high school students to think on their feet about fundamental scientific concepts. I look forward to the development of future programs in the Learning Laboratory series. They are sorely needed, and I for one will be waiting to gobble up any more offerings of the Food Chain variety!

Dean Goodwin taught biological chemistry and carried out research in mechanistic organic photochemistry at The City University in London, England, prior to his move to USA. Dean holds a bachelor's degree in Biochemistry (Salford University, England), and a combined Ph.D./PGCE in Chemistry/Science Education (Leicester University, England). He has been involved in designing and implementing environmental curricula since the late 1980's and is currently Director of Environmental Education at Kimball Union Academy in Meriden, NH. He teaches a variety of environmental courses up to the Advanced Placement level, utilizing an experiential, problem-based learning approach. He has run many workshops and institutes for environmental science teachers. Dean is a Question Leader at the AP Environmental Science examination reading each year, the Content Advisor for the College Board's AP Central Environmental Science website, and has recently been appointed to the AP Environmental Science Test Development Committee. Currently, he is on sabbatical working on an environmental science lab project in conjunction with the College Board and the Environmental Literacy Council.