A Note to Teachers

This is a Computational Science PBL that involves cross-curricular collaboration between math and science classes. The problem originated with Chemistry 2 students in spring 2001. These students responded to a letter from Mrs. James asking them to investigate the CO₂ levels in her classroom. The students developed the experimental design and collected and analyzed the data. This initial data was used to help design a preliminary model. Future students will use STELLA modeling software to develop their own conceptual models of change in CO₂ levels then correlate this model with their experimental data.

The Problem Based Learning philosophy encourages presentation of a messy open-ended problem in which the curriculum is imbedded. This particular problem certainly meets those criteria. It is indeed messy and is as open-ended as the instructor will allow. We encourage you to let the students do as much of the thinking and design as they can manage while you coach them toward the learning that fits the lesson objectives. A traditional approach would require the students to follow a prewritten lab procedure, look at a teacher-created STELLA model, and see whether they had come to the "correct answer." Students will learn more if the instructor can be patient and brave enough to stand back and let the students wrestle with the problem, form their own models, compare the model with the experimental data, and come to conclusions on the validity of the model using experimental data.

Various levels of mathematical analysis are contained in this problem. We decided to involve our math classes throughout the entire analysis process. Memos from the science classes are sent to the various math classes. For example, the data that was collected seemed to be curved. The science class sent the data to the Pre-Calculus class to analyze and give them an equation that model the data. This does take collaboration with your math department. Rubrics are included for the math classes and are adjustable.

The entire PBL could be done by one set of classes, but there is benefit to be gained by involving students at several different levels and in both science and math. We have chosen to involve five different classes in this project, two science classes and three math classes. Students will produce a better product if their peers are the audience.