Research: Science & Education
Evaluation of Learning Processes in an Organic Chemistry Course B. Maroto, C. Camusso, and M. Cividini Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba. C.C. 509. Córdoba, Argentina The present study is part of a series of evaluations done on student learning processes in organic chemistry. In a previous study, students’ knowledge after completion of the introductory organic chemistry course was assessed using a multiple-choice exercise. The results of that study showed that 83% of the students tested were able to give a description of the problem presented, analyze it, and establish partial relationships among its elements, with 27% of those students succeeding in making a partial synthesis of the information as well (1). In order to expand our assessment of learning, the present study looks at a more subjective exercise completed by students at the end of each unit. The purpose of the exercise was to evaluate the learning processes present in units 1 through 6 of the organic chemistry program, using carbohydrate, lipid, and protein molecules to carry out this evaluation, which was designed based on Ausubel’s (2) concept of “meaningful learning”. Meaningful learning entails the assimilation of newly presented concepts through their differentiation or integration with previously learned information. Once connected to preexisting concepts in the student’s cognitive structure, the new concepts are said to become “significant.” Our study focused on the concepts presented in six units, as follows: Unit 1: Introduction to the Chemistry of Carbon Unit 2: Hybridization and Bonding Unit 3: Isomerism Unit 4: Reaction Kinetics Unit 5: Functional Groups Unit 6: Chemical Reactions
Methodology A total of 71 students participated in the study, divided into three groups of 15, 28, and 28 students, respectively. The study took place during the regular class time of each group and was administered by a different instructor in each case. Students were given an exercise booklet at the beginning of the course, in which the same three molecular compound formulae were provided as follows: Compound No. 1: Haworth formula for saccharose Compound No. 2: Formula for a phospholipid Compound No. 3: Formula for a polypeptide
Upon completion of each unit, students were instructed to answer the question: “What can you say about these three organic compounds?”, and to record any new concepts, information or analyses pertaining them. Over the period of study, the students analyzed biomolecules in terms of bond, polarity, and physical properties (upon completion of unit 2); structural disposition of molecules (upon completion of unit 3); chemical reactivity (unit 4); functional groups (unit 5); and possible reactions (unit 6). However, no discussion of molecular family/group (i.e.,
carbohydrates, lipids, or proteins) took place in class. These concepts are not presented until later in the course, and we hoped that students would be able to infer this information on their own, as evidenced in their answers in the workbook (3). After collecting the students’ completed workbooks, their answers were categorized according to the following criteria: A: partial synthesis of the material B: analysis of the problem C: description of the problem D: incorrect answer E: no answer
These categories were created in order to facilitate the analysis of students’ answers in terms of the thinking processes that led to those answers within the theoretical framework of meaningful learning, that is, how students applied the concepts presented in each unit. Student responses falling into categories A, B, and C imply that the student was able to give accurate information using thinking processes of varying degrees of complexity, namely, synthesis, analysis, and description. Categories A and B involve the processes of abstraction, differentiation, and generalization. Students who gave responses on this level were not only able to recognize constituent elements of a compound, but to infer new and broader relationships. This would indicate that the students went through an active process of recognition of the information provided in theoretical classes and seminars, and established relationships between that information and the concepts presented in previous units. Based on this integration of new and previously learned concepts, the students were able to analyze and explain the significance of the compound within the context of each unit. Students categorized as C demonstrated recognition of some of the elements of the compounds. However, identification of the elements of a compound alone is not sufficient to establish relationships among the elements; only a description was given at this level. Results and Discussion Students’ comments on each of the three compounds were analyzed comparing the values for each category (A– E) in each unit (1–6). There were no notable differences among student responses per compound. However, when evaluated in terms of the successive units covered, there were important differences in percentages of students in each category (Figs. 1 and 2). Students’ answers can be separated into two groups: those fitting into categories A, B, and C, and those that are categorized as D and E. Answers categorized as A, B, or C consist of those in which the student has demonstrated the ability to answer correctly regardless of the different thinking processes or varying levels of complexity entailed in their answers.
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Figure 1. Percentage values obtained for each category in Unit 1 for compounds 1, 2, and 3.
Figure 2. Percentage values obtained for each category in Unit 6 for compounds 1,2, and 3.
It is assumed that the student who is able to explain a given phenomenon must have previously gone through less complex thinking processes, that is, analysis (B) and description (C). The second group of students are those who responded incorrectly (D) to the main question or who gave no response at all (E). Based on Ausubel’s (2) analysis of the use of concepts, thought processes such as description are understood to imply what he refers to as “the perceptual use of concepts”. These processes include basic forms of receptive learning where “a new and fairly obvious representational member of a set is presented in order to illustrate or support a previously existing concept in the learner’s cognitive structure”. The perceptual use of concepts is also at work when “the learner demonstrates immediate comprehension of previously learned and therefore, significant concepts and propositions, when encountered on subsequent occasions”. The percentage of students whose answers corresponded to category C were those that demonstrated recognition of the elements of the compound presented. However, the mere identification of these elements does not allow for the establishment of relationships amongst them, nor does it allow the student to put the recognized concepts to use—he can only describe what he observes. Thus, these students are considered to be applying a perceptual use of the concepts. This perceptual use of concepts is important in that it is entailed in what Ausubel refers to as “the cognitive use of concepts”, which implies learning by reception and discovery. This process involves a cognitive characterization in which new and related concepts, subconcepts, and propositions are acquired and assimilated in more inclusive propositional or conceptual entities. Learning by discovery entails the simplest to the most complex types of problem solving in which not only does the learner have to formulate the problem, such as in the special case of a more general concept or proposition and/or meaning, but in addition, he must extend, elaborate, limit, or reorganize previously existing concepts or propositions. The cognitive use of concepts in this type of learning necessitates constant processes of abstraction, differentiation, and generalization, which were characteristic of students’ answers in categories A and B. Achieving these categories implies that they were able not only to recognize the elements that make up a given compound, but also to apply new, more inclusive meanings to them. This implies an active process of recognition of the elements presented in theoretical classes as well as those discussed in seminars, and the ability to relate these to previously presented concepts. It also entails the ability to differentiate these elements and integrate them with relevant, already-existing concepts in order to analyze and explain what the compound represents within the parameters of each individual unit of study.
Although students answering in categories D and E did not demonstrate accurate use of the concepts presented, it may be useful to differentiate these two levels of answer over the course of study, since the number of students who did not understand the question appeared to decrease over the course of study, while the number of students not answering increased. It is possible that the solving of numerical problems in the course units prior to those included in this study is related to concrete practice—that is, connected to memory. This in turn could be related to the increasing tendency towards no answer at all as the concepts become gradually more difficult. In spite of the fact that the three compounds were macromolecules (biomolecules), each with its own particular characteristics and properties, they all suggested very similar patterns in the students’ answers. Upon completion of the study, the response graph (Fig. 2) indicated that that frequency of values for A and B increased at the expense of those for C, which showed a decrease compared to responses at the beginning of the course (Fig. 1). This indicates that a high percentage of students demonstrated “meaningful learning” in their assimilation of the concepts presented in the units studied, deducing physical and chemical properties of the biomolecules (types of bonding, polarity, solubility, possible reactions, etc.). This was achieved only with the knowledge of their molecular structures. Based on this observation, students who demonstrated the cognitive processes represented by categories A, B, and C were able not only to manage the analytical content of each unit, but to draw conclusions based on the macromolecules as well, even when they could not clearly identify them as belonging to any particular group of biomolecules. This would allow us to infer that these students could solve similar problems involving any other type of complex molecule (vitamins, hormones, agrochemicals, etc.) without memorizing their molecular properties. As a closing exercise, a cellular membrane diagram that integrated the molecular groups was presented at the conclusion of the six units. Class discussion of the functional relationships based on their constituent elements contained in the diagram followed. The diagram was completed by only two of the three groups (50 students). The data obtained confirmed the general tendency towards decreasing percentages of inaccurate responses. At the same time, it showed higher percentages in the number of students able to give a description (C) or analysis (B).
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Literature Cited 1. Maroto, B.; Camusso, C. J. Chem. Educ. 1996, 73, 231. 2. Ausubel, D. P; Novak, J. D.; Hanesian, H. Educational Psychology, 2nd ed.; Holt, Rinehart and Winston: New York, 1978. 3. Raths, J. S. Educational Leadership 1971, April, 716.
Journal of Chemical Education • Vol. 74 No. 10 October 1997
