Problem-based Cooperative Learning Situations in the Analytical Chemistry Teaching Laboratory and Classroom:

Making the Most Effective Use of Class Time?

 

Julian Tyson

Department of Chemistry

University of Massachusetts

Amherst, MA 01003

 

            Chemistry 312 is a one-semester course for non-chemistry science majors that meets for three 50-minute classes per week, and has one four-hour lab per week.  Semesters are 13-14 weeks long.  Over the past three years as a result of curricular revisions catalyzed by (a) the award of an NSF-ILI grant, (b) the publication of the NSF’s Curricular Reforms in the Analytical Sciences and (c) my involvement in STEMTEC, the local NSF-funded center for excellence in teacher preparation, ‘research projects’ have been introduced into the laboratory class, cooperative learning situations have been ‘imposed’ on the students in the ‘lecture’ class, and students have been encouraged to work cooperatively outside of the classroom on homework exercises, lab reports, and the K-12 teaching experience. 

             The results have been encouraging in that (a) the performance of the students, as evidenced by the distribution of letter grades awarded, has significantly improved since these modifications were introduced, and (b) student feedback about the pedagogies employed have been generally (though not 100%) positive.  It is also clear (though the numbers involved are small) that students who do not connect with other members of the class are often the ones who withdraw.  The response to the requirement to interact with K-12 classes has been uniformly positive.

             The last three periods of the laboratory class have been given over to a research project. A significant challenge for the instructor has been to devise projects that are (a) ‘real world’, (b) are not so challenging that no progress is possible with the limited equipment and time available, and (c) not so trivial that they do not catch students’ interest.  This year, project topics were given out two weeks prior to the first project lab period, and preliminary background reading and suggestions for a plan of work (together with details of chemicals and solutions needed) were required as a graded homework exercise whose deadline was just prior to the start of the project.  Six projects were assigned.   These involved the development of an analytical method, followed by validation and application to a real sample material.  As far as possible, the exercises were constructed around a ‘problem’ which, for its solution, needed information about the chemical composition of relevant materials.  For example, one project involved testing the hypothesis that cigarette butts are a significant source of environmental contamination by phosphate; another project examined the extent to which nutritional elements were extracted from tea leaves by soaking in hot water.  A report in the form of a short paper for a research journal was required. 

             The success (or otherwise) of this part of the course will be described, information from the students will be presented, and some critical comments made as to whether such exercises are the best use of class time. 

             One issue that only surfaced about half way through the semester was that students did not have the mastery of some basic chemical facts and concepts that I thought they would have as a result of taking the prerequisite courses of general chemistry and organic chemistry, even though an early diagnostic homework on relevant topics showed no difficulties.  The most critical manifestations of this problem were that students were not only very slow to perform basic calculations concerned with concentrations and dilutions, but were also prone to make errors or to make inappropriate choices of masses and volumes of relevant chemicals and solvents.  Thus, a disproportionate amount of laboratory time was spent on these preliminary aspects of the experiments.  This suggests that too much detailed information was being provided in connection with the earlier experiments.  Even though students had performed several experiments already in the lab before the projects started, they had not, apparently, improved in terms of the speed with which they could perform appropriate calculations nor in terms of the reliability with which they could make decisions about basic procedures.

             This experience suggests that additional tutoring is needed.  One possibility is that material could be delivered via the web in a manner similar to that for the OWL material already developed in the Chemistry Department in connection with general chemistry, and currently under development for use with sophomore organic classes.  Delivery in this form could have the advantage that revision of these basic concepts and skills would not take up class time--currently, I am devoting 10-15 minutes of every ‘lecture’ class to such remedial topics--though I am finding that unless I test the students in class under my supervision, I do not get accurate information about their abilities.