Discovery Chemistry A Laboratory-Centered Approach to Teaching General Chemistry Robert W. Riccl and Mauri A. Diizler College of the Holy Cross, Worcester, MA 01610 Recent reports sponsored by the National Science Foundation ( I ) and Sigma Xi (2) stress the need to attract undereraduates to careers in science. This national concern has ;so attracted attention in this Journal ( 3 , 4 ) .These reports recommend systemic changes in chemical education, particularly a t the introductory course level. Several of the recommendations focus on revitalizing the lecture content and repairing the deteriorated and outdated laboratory infrastructure. In response to these and other issues, the Chemistry Department a t Holy Cross1 has developed a laboratory-cen&red approach to the teaching of general chemistry that we call Discovery Chemistry. The purpose of this article is to report on the~successwe have had with our new program.
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The Prwram Experimentation is the lifeblood of a science and is essential to the nourishment of the ideas and thoughts that we bring toourstudents. Ifwe,as scientistsand educatun, truly believe that the heart of chemistry is experimentation, then we should strive to make the laboratorythe centerpiece of a student's learning experience. New topics in chemistry should be introduced first in the laboratory and then discussed more fully later in lecture. This inductive approach to teaching chemistry enhances the importance of the lahoratory experience in the minds of our students, who all too often fail to appreciate the important role played by their weekly laboratory meetings. Of course, the traditional verification laboratow format must he changed if we are to give priority to the ~aborator~over the lecture in theintroduciion of new ideas. In i h place we must adopt a Guided Inquiry or Discovery approach.
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Journal of Chemical Education
Discovery Approach The Guided Inquiry or Discovery approach to the teaching of general chemistry laboratory is not new to the readers of this Journal (5,6).Indeed, the approachis probably as old as science teaching itself. Discovery Labs, unlike verification labs. illustrate the scientific method. Each lab can have a component of data gathering, data analysis, hypothesis formation, and hypothesis testing. Also, the Discovery approach emphasizes the connection between a theory and the supporting empirical data. This is particularly important where the relationshin is not obvious. as in the case of the theory of atomic and molecular structure and the supporting snectrosconic evidence. ~t ~ o l 'Cross y we have expanded the Discovery concept so that it has become the driving force behind the teaching of general chemistry. An essential feature of all our Discovery Labs, which cover the entire field of general chemistry, is the collection of a large database. Each student contributes individuallv and cooperatively to the database, which is then used b; the studknts, with the help of their instructors, to develop models and theories. In a typical Discovery Lab a t Holy Cross the students attend a prelab meeting where they receive detailed directions on experimental techniques and safety procedures.
' Holy Cross Isa liberal arts college of 2500 students. The Chemis
Department, which has graduated an average of 34 chemslry majors per year since 1979, is statled with nine faculty msmoers and three lab supervisors. Approximately 200 students per year enroll in general chemistry Our typical student has a combined SAT score of try
1200.
2.004 40
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60
70
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Year of Minting Figure 1. Pwied student data tor the mass of American l a coins of various mint years versus the year the coin was minted. The composition of the coin was changed in 1982.
These include precautionary notes on both the handling of chemicals and the operation of electrical equipment. However, a t this meeting the students receive very little instruction on the underlying theory. In the laboratory, all the students carry out the same general procedure, though each is required to run the experiment under a slightly different set of conditions. For example, in a kinetics experiment, each student may be assigned the same reaction but must investigate it under a unique set of conditions (i.e., reactant concentration, temperature, etc.). Or perhaps the students may be divided into several groups, each to study a different but related reaction. Following the lab, which may take 2 or 2% h to complete, the studentsassemble for a postlab meeting. At this meeting the students pool their data and, under the guidance oftheir instructorlare led to discover some principle or concept based upon the analysis of the shared information. Three major issues had to be addressed before the Discoverv annroach could be success full^ " annlied .. to the teaching- of general chemistry. First, could college students-particularIv those with little or no nrevious lab experience-obtain data that was precise and accurate enough provide a guide toward an understanding of some principle or concept in chemistry? Second, couldkxperime~tsbe designed to enable students to participate in developing original explanations for experimental observations, and-to what extent could their hypotheses be tested and modified within the constraints of a single laboratory period? Third, would it be possible t o design aseries of experiments that would encomnass the entire ranee of subiect matter normallv covered in general chemistry k u d i n i atomic and moleklar structure? The remainder of this article will demonstrate how we successfully addressed these issues by citing several examples taken from our Discovery Labs.
