The Case of Organic Chemistry

Research: Science and Education edited by

Chemical Education Research

Diane M. Bunce The Catholic University of America Washington, D.C. 20064 Amy J. Phelps Middle Tennessee State University Murfreesboro, TN 37132

The Role of Structure of the Discipline in Improving Student Understanding: The Case of Organic Chemistry Gail Green* and Marissa Rollnick

School of Chemistry and College of Science, University of the Witwatersrand, P.O. Wits 2050, Johannesburg, South Africa; *[email protected]

Many instructors would be gratified if they were able to identify a concept that students struggle to internalize, to implement an intervention, and then be rewarded with concrete evidence that the intervention significantly improved student learning. This was the case in second-year organic chemistry at this university where an intervention by a concerned instructor (1) was able to transform the organic chemistry module from one of the most difficult of six modules to one of the easiest, not only in terms of student performance, but also in how students perceived the module. It is often the case in naturalistic research that important observations are unanticipated. Interest in the turnabout in organic chemistry was kindled during a larger study where the primary focus was on providing a holistic description of students’ experience of second-year chemistry (2). Analyses of the various chemistry subdisciplines prompted a closer look at what had happened in organic chemistry to investigate the possibility of replicating what had been achieved in other problematic branches of second-year chemistry. The aim of this article is to explore the factors surrounding the intervention in organic chemistry. More specifically, we aim to show that in this particular instance the catalysts for success were the • Structure of the content of organic chemistry (3, 4) • Pedagogical content knowledge and enthusiasm of the instructor (5, 6) • Presentation of the organic chemistry module within the context of normal science education (7)

Background and Context It is a common experience that courses, even within a particular discipline, differ with regard to their difficulty. This notion of “difficulty”, though on the surface self-explanatory, is an elusive concept. It can be linked to the nature of the content, the nature of the teaching, to the cognitive level at which questions are posed during formal assessment, and most importantly to the students’ perceptions of the content as they are exposed to it. Individual performance in a discipline is usually the most important factor in a student’s perception of its difficulty, but for instructors, “difficulty” usually becomes an issue only when the majority of students do not fare as well as anticipated in any particular course. We have

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been concerned about student performance in the secondyear classes for a number of years. Second-year chemistry at this university differs substantially from the typical U.S. second-year experience as this course comprises six chemistry modules offered over two semesters. During the first semester students take physical and inorganic chemistry as well as introductory spectroscopy, followed by organic, analytical, and materials and solid-state chemistry in the second semester. All modules have 24 formal teaching hours allocated for tuition except spectroscopy and materials chemistry that each run over 13 hours. It has been shown (2) that students fare significantly worse in second-year courses compared to first-year chemistry courses and that second-year students predictably find some chemistry subdisciplines more difficult than others. The tendency has been to focus on chemistry content when seeking explanations for difficulty, but it is conceivable that difficulties experienced by students might not only be related to the nature of chemistry, but also to the structure of the discipline. Caldin (8), writing in HYLE, a journal devoted to the philosophy of chemistry, considered the following five issues as basic to the nature of chemistry: 1. The nature of scientific generalizations 2. The distinction between theories and laws 3. The question whether theories are explanatory as well as instrumental 4. The status of theoretical entities such as atoms 5. The question of the use of new observations in relation to theories

All of these issues refer to the discipline of chemistry as a whole. The three ways of representing matter in chemistry are an aspect of its nature contributing to the difficulty of the subject (9). Erduran and Scerri (9) point to the difficulties experienced by students in advanced chemistry with many aspects of the discipline and postulate that a knowledge of the nature of chemistry would make a significant positive contribution to instructors’ pedagogical content knowledge (PCK) (5, 6). The structure of chemistry on the other hand, refers to the logical organization of the concepts and models of chemistry. There have been attempts to clarify issues surrounding the structure of chemistry. Jensen (4) has suggested that the

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Research: Science and Education

concepts and models of chemistry can be sorted into nine characteristic categories that form the backbone of the structure. De Vos et al. (10) have identified the key concepts of chemistry as chemical substance and chemical reactions. The curriculum built around these concepts is described as “one large quest for hidden factors that determine chemical change and the creation of new substances”. Others (2, 3) have described the structure in terms of sequencing of concepts. It appears that most curricula focus on specific concepts to be covered, while much less attention is directed at how the concepts should be embedded in an overall conceptual structure (10). Structural differences between subjects are also often ignored. There is a fundamental difference in the structure of the subjects physics and chemistry—physics is characterized by mathematical applications while chemistry focuses on modeling. However, starting from high school, there is generally little differentiation in the teaching of the two subjects beyond the obvious conceptual variation between the disciplines (9). A survey of the newly-emerging field of philosophy of chemistry similarly reveals little concern about possible differences between the subdisciplines of chemistry. A possible explanation for the difficulties experienced by students in advanced chemistry could therefore lie in the structural differences of the various subdisciplines, rather than in the difficulty of concepts or how concepts are developed. These ideas have been represented in the teaching context by Gabel (11) who postulates that the structure of a discipline such as chemistry may itself be an instructional hindrance. Research into instructors’ subject matter knowledge has recognized for some time now that effective instructors at all levels employ more than content knowledge per se for teaching. In fact, instructors rarely teach the content knowledge of the subject in the form that it is stored in memory, generally transforming their content knowledge into a form that is both suitable for teaching and can be understood by the students (12). This transformed knowledge used in teaching has been mentioned before and has been identified by Shulman (6) as pedagogical content knowledge (PCK). He has described PCK as the “distinctive body of knowledge for teaching and as the professional knowledge base of teachers” (6). Ball, Bass, and Hill (13), working in mathematics, show that this is a specialized form of subject matter knowledge: [O]ur example also points up that there are predictable and recurrent tasks that teachers face that are deeply entwined with mathematics and mathematical reasoning. Figuring out where a student has gone wrong (error analysis), explaining the basis for an algorithm and showing why it works (principled knowledge of algorithms, and reasoning), and using representations. Important to note is that each of these common tasks of teaching is as much a mathematical undertaking as it is a pedagogical one.

There are many excellent examples of PCK in action where university professors, who are usually not trained teachers, show the ability to integrate knowledge of students, subject matter, pedagogy, and environmental context, into their teaching. This is manifested in many ways, for example through use of analogies (14), employing student-taught re-

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view sessions (15), or using knowledge of the structure of a chemistry subdiscipline to plan an intervention (1, 3). A third aspect contributing to the difficulty of a subject is the nature of the teaching, whether it takes place in the context of normal science education (NSE) or critical science (7). These ideas originate from Kuhn (16) who claimed that NSE initiates and prepares students for the handling of normal science problems “that is for the activity of puzzlesolving as set within the current paradigm or disciplinary matrix, which is all that future normal scientists need in order to function successfully” (7). NSE provides a relatively dogmatic initiation into a pre-established problem-solving tradition that the student is neither invited nor qualified to evaluate (7). On the other hand, one of the stated aims of a university education is to encourage a much more fluid approach to science that involves what can be called critical thinking. This would require active involvement of students in processes of enquiry such as reasoning, observing, and experimenting (7). It has been proved that it is possible to implement modest forms of critical science education (7, 17). However, in the face of criticism, Kuhn (16) continues to dispute the possibility of training students for the practice of revolutionary or critical science and strongly contends that the practices of normal science are sufficient for aspiring chemists. Data Collection As mentioned, this article is part of a larger study (2) where a large quantity of both quantitative and qualitative data were collected about students’ experiences in second-year and first-year chemistry. Data relevant to this article were generated by student questionnaires, interviews, analysis of examinations, examination results, perusal of course materials, and field notes taken during classes. The intention is to evaluate factors that might have contributed to success of a program thereby stimulating discussion around these issues. Identifying Difficult Subjects As part of the original study the difficult second-year modules for the period 1996 to 1998 were identified by triangulating data from student interviews and questionnaires with data obtained from analysis of examination scores in different modules. Both qualitative and quantitative data gave the same ranking of modules in terms of difficulty. When we studied the data for the three years in question we noted that second-year chemistry students had historically struggled most in physical and organic chemistry, with the trend being reversed in 1998. This observation was initially puzzling until further investigation revealed that there had been one small change in the teaching strategy used in organic chemistry in 1998 (1). Once more data were available we were able to confirm that the change in organic chemistry scores was sustained while the particular teacher was in charge of the course and the intervention. It appears that an intervention alone is not sufficient—the instructor in charge also has to be convinced of its merit. After the instructor who achieved the initial success passed away in 2000, organic slowly regained its place as one of the more difficult subjects. Even if


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Table 1. Ranking of Second-Year Chemistry Modules According to Examination Averages Ranking

Year

1

2

3

4

5

6

1996

Analytical

Spectroscopy

Inorganic

Physical

Materials

Organic Organic

1997

Spectroscopy

Inorganic

Analytical

Materials

Physical

1998

Materials

Organic

Analytical

Spectroscopy

Inorganic

Physical

1999

Materials

Organic

Inorganic

Spectroscopy

Physical

Analytical

2000

Materials

Spectroscopy

Inorganic

Organic

Analytical

Physical

2001

Materials

Spectroscopy

Physical

Inorganic

Organic

Analytical

NOTE: The ranking scale goes from easiest (1) to most difficult (6).

Table 2. Cognitive Abilities Evaluated in Second-Year Organic Chemistry Level

Year 1996

1997

1998

12 (15.5%)

11 (15.5%)

35 (59%)

63 (78%)

63 (69%)

08 (13%)

05 (6.5%)

11 (15.5%)

I

17 (28%)

II III

a

a

Number and percent of student scores at each level.

organic results are viewed separately from those of other subjects, the dramatic improvement in the scores for 1998 to 2000 are remarkable. Table 1 shows ranking according to examination results from 1996 to 2001. The ranking from 1996 to 1998 corresponds with the views of students on the difficulty of the modules. The intervention that caused the initial shift was simple. Each student in the class was required to prepare a poster illustrating key principles of certain types of organic reactions. During a feedback session they then presented and explained what appeared on their posters. Students were to assume that they had just devised the technique of using curved arrows to show the movement of electrons during the course of an organic reaction. This intervention, for which an afternoon was set aside, has already been described in this Journal (1). Others (15) have used similar strategies where presentations by students are used to enhance the concepts for both the individual giving the presentation as well as for the class as a whole. Open-ended learning environments like these (1, 15) afford students the opportunity of improving their metacognitive skills (18). Metacognitive knowledge includes knowledge of general strategies that can be used for different tasks and knowledge of the conditions under which these strategies can be used (18, 19). The project in organic chemistry was designed to • Show students that electron movement is a common feature of all organic reactions (this stems from subject knowledge, but is a fact that they seemed to have missed). • Enable students to predict the direction of electron movement (from knowledge of electronegativity). • Force students to engage with the module by requiring them the do a presentation and answer questions.

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Since there were different examples of specific reaction types on each poster, this enabled students to relate the new information on successive posters to the basic principles governing structure–reactivity relationships in organic chemistry. This active participation ensured the carry-over of concepts into long-term memory, which has been shown to contribute significantly to establishing an organized knowledge structure (3, 20). We recognize that student groups from year to year taking the same course are not academically equally strong and that this can cause scores to fluctuate, but in this case the 1998 class was a low-performing group compared to classes from previous years with only one A-student among them (1). Our study also revealed that there had been no substantive changes to the teaching staff or to the cognitive level of questions in any of the modules in 1998 that could have conceivably made the other modules more difficult for students. In organic the same female instructor was in charge from 1996–1999. The cognitive level of all questions in examinations across all modules was evaluated for 1996–1998, using a simplified taxonomy derived from Bloom (21). The criteria used to asses the cognitive levels were very similar to those used by Zoller, Dori, and Lubezky (22) and our levels I, II, and III correspond to their algorithmic, lower-order, and higher-order cognitive skills, respectively. Although a discussion of the allocation of cognitive levels to examination questions is an interesting subject, it is not the main focus of this article and further information about how we went about it is available in the conference proceedings of the Southern African Association for Research into Mathematics, Science and Technology (23). We found that level II testing predominated across all modules for the three-year period. To support our claim that it was not a change in the cognitive level of organic examinations that caused the improvement in scores, data for 1996 to 1998 are shown in Table 2. The predominance of level II testing in the second-year chemistry examinations is not unexpected since it appears to be a worldwide phenomenon (17, 24). For questions to be classified as cognitive level III criteria of novelty and unfamiliarity, necessitating mental restructuring were imposed. On this count the 1998 examinations are shown to have been marginally more difficult than those of 1997 and it might have been expected that scores should decrease slightly as shown by Zoller et al. (22). In addition the structure and


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format of the organic exams were very similar from 1993 to 1998, which eliminates the possibility that so-called test wiseness could have caused the improvement or else the improvement would have started earlier. Taking all of this into account, the turnabout in organic chemistry performance becomes all the more noteworthy. Characteristics of Knowledge in Different Chemistry Modules The obvious explanations for the improvement, that is, opportunity for reinforcing knowledge have been discussed. However, during analysis and comparison of second-year course materials we uncovered another factor that might have facilitated the success of the intervention in organic chemistry in particular. It appeared that the second-year chemistry modules are inherently different in structure as well as content. This was a characteristic not only of the modules, but of the subjects themselves. Subject content always seems to be arranged in the same way, no matter where it is presented. Kuhn (16) suggests that textbooks that compete for adoption in a particular course differ mainly in level and in pedagogic detail, not in substance or conceptual structure. In some subjects knowledge construction and concept development appear to occur in what we termed a linear fashion. In these subjects, comprehension of later concepts depends on understanding of concepts that have been covered earlier. On the other hand, there are other chemistry fields where later ideas can be fully understood independently of comprehension of earlier ideas. In this case, course development would be described as nonlinear or branched. Bernstein (25) has postulated a similar model for knowledge and discourse structures. He differentiates between horizontal and vertical knowledge and discourse structures, describing a horizontal discourse as one that is segmentally structured, with each discrete segment containing its own assemblies of possibilities. The parallels with the nonlinear course development according to our model are obvious here. Bernstein’s model is designed with sociological purposes in mind, while it can be argued that the theory of linear and nonlinear progression of concepts is in the cognitive domain. The model of linear and branched subjects can be considered flawed to the extent that it takes no account of cross-linking between concepts in what are viewed as branched courses. The structures for the different second-year chemistry modules at our university are in Table 3 below. The unique problems we encountered with classification of organic chemistry will be discussed separately. What Is Special about Organic Chemistry? To anyone looking through an organic textbook, the seemingly divergent themes that emerge in different chapters might at first sight cause the subject to appear branched in structure. Some textbooks, for example, use functional groups as their organizing principle, while others organize content around bonding (single, double, triple bonds). After much reflection we decided that organic chemistry differs fundamentally from all other chemistry subdisciplines, possessing a few, identifiable, fundamental concepts, principles, and

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Table 3. Nature of Concept Development in Chemistry Subdsciplines Subdiscipline

Concept Development

Physical Chemistry

Linear

Quantum Effects

Linear

Thermodynamics

Nonlinear

Inorganic Chemistry

Nonlinear

Analytical Chemistry

Nonlinear

Spectroscopy Chemistry

Nonlinear

Materials Chemistry

Linear

Organic Chemistry

Linear

conventions that underpin the entire discipline and permeate all sections. These are the characteristics of a linear subject. Taagepera and Noori (3) faced a similar dilemma when they tried to decide whether it was possible to construct a hierarchy of concepts in organic chemistry and whether it was possible to identify an organizing principle. In the end they concluded, as we had, that the central organizing principle in organic chemistry is the concept of electronegativity, which is used in prediction of electron densities (3). With regard to reaction mechanisms, a convention widely used in organic chemistry in representing suggested and proven mechanisms of reactions, involves the use of curved doubleor single-headed arrows to show direction of electron movement. These fundamental ideas are introduced early in the course and subsequently used in all later sections. Students who have not managed to identify the organizing principle, resort to memorization of specifics for tests, which are forgotten soon after as lack of an organizing principle prevents the carry-over of concepts into long-term memory (3). How Does the Difficulty of a Module Relate to Its Structure? We found no pattern to the way in which the different chemistry modules developed. It appears that the linear or nonlinear progression of a course is determined by the nature of the content taught and not by intent on the part of curriculum designers. This led to speculation about the impact of the branched or linear nature of a course on its difficulty. Intuitively one might expect that a linear development, where there is a continuous building and extension of concepts that rely on mastery of earlier concepts, should be more problematic to students. The modules physical (particularly quantum chemistry), materials, and organic chemistry were all identified to have a linear progression (Table 3). In 1996 quantum and organic chemistry were identified as most difficult modules from examination results, questionnaires, and interviews while the other linear module, materials chemistry was identified by the same sources generally as one of the easier modules. Based on this information it seems reasonable to conclude that the structure of a course, although important, is but one determinant of the difficulty of the course, and that the nature of the material taught also has a major influence. However it is important to note that in the case of a course with a linear structure, a single basic concept has


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the potential to hinder or enable access to the whole module. It can be postulated that one of the reasons why there might be problems in replicating what happened in organic chemistry in other subdisciplines, lies in the innate characteristics of the subject itself. It seems reasonable to assume that while a single intervention might bring success in a linear discipline, a number of actions might be needed in a branched subject, unless all the problems could be traced back to a particular branch of the content. The findings of Zoller (26) concerning misconceptions in first-year chemistry seem to support this. This study reported that there were no logical relationships between misconceptions at first-year level. This is probably due to the fact that first-year chemistry is not a single subject but consists of a number of subdisciplines lumped together in a branched structure. Interventions in subjects having a clear organizing principle are easier to put in place and these subjects seem inevitably to be linear in structure. Effect of Pedagogical Content Knowledge of the Instructor In the second instance, we were compelled to conclude that the transfiguration brought about by the compulsory organic chemistry poster presentation can also be traced back to the instructor’s knowledge of how to teach the subject in relation to her understanding of the discipline. The truth of this assertion will be clear to anyone reading her article (1) in this Journal. In other words, the intervention resulted from pedagogical understanding of the subject, which is usually dependent on the quality of teaching experience that any person has had. Obviously, there are many facets to PCK and it will only be possible to discuss a few of these here. The instructor was a content expert with an additional teaching qualification that made it possible for her to reflect on what she was doing. She was aware that the poor performance of most students in organic chemistry stemmed from general difficulties the class were experiencing with the use of arrows to show direction of electron movement (1). PCK (6) influences the act of transforming content so students are able to cope and is gained not only through experience, but also by reading. The instructor who implemented the successful intervention confesses in her article (1) that she continually reflected on her teaching practice and kept abreast of the literature in an attempt to find ways of increasing student participation and achievement. In this case, reflecting on the structure of the discipline enhanced the instructor’s PCK so that she was able to find ways of achieving her objectives. A second aspect of her PCK is evident in her diagnosis of the root of the problem that students were having with showing electron movement in organic reactions. Knowledge of what action would be appropriate and why, is a further aspect of PCK. Although it is accepted that learning occurs through practice and feedback (24) it is often difficult to get students to do the repetition they need to acquire a particular skill. The intervention forced students to engage with and practice applying the fundamental concepts and conventions of organic chemistry, while the real-

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ization that this was necessary came from the PCK of the instructor. The poster prepared by each student was not as important as the interaction during the presentation, where an instructor would probe for evidence of understanding. An extract from a typical interaction, reported by Huddle (1), is repeated below for easy reference. This extract illustrates only a few of the many concepts that have to be understood before curved arrows can be drawn with confidence. Instructor: I see you have a new idea to explain the mechanism of organic reactions. Student: Yes, you can use arrows to show the direction of electron movement. Instructor: How do I know where to draw the arrows? Student: They are always drawn from the nucleophile, the electron-rich center, to the electrophile, an electron-deficient center. Instructor: How do I decide which is the nucleophile and which the electrophile? Student: It is dependent on the electronegativities of the various atoms. For example, in the C⫺O bond, oxygen is more electronegative than carbon, so the oxygen atom would be the nucleophile and the carbon atom the electrophile.

The questioning continues in this vein, probing understanding of when to use double- or single-headed arrows and how to decide whether a bond will break homolytically or heterolytically (1). In cases where it was evident from the presentation that a student had not yet mastered some of the concepts, Huddle (1) reports that some time was spent with that student in an attempt to ensure that all the underlying knowledge was in place. Operating within the Boundaries of Normal Science The third factor contributing to the success of the organic chemistry intervention is the fact that the teaching in chemistry at this university can be described as normal science education (NSE) and not as education for critical science (7). Scrutiny of the practices in organic chemistry reveal that one of the main purposes of the intervention was to provide students with the tools for increasing understanding of known or similar puzzles involving curved arrows, closely modeled in method and substance on given exemplars. Activities in this domain are those of NSE (7). Understanding of the fact that chemistry teaching involves puzzle-solving would have been part of the instructor’s PCK. Had the intervention been applied within the context of critical science, it is predicted by Van Berkel et al. (7) that this would have required a far more complex and long-term intervention aimed at paradigm change, which would not have been be detectable in one year. Conclusion We have explored the factors that might have contributed to the success of the intervention in organic chemistry and have presented some views on why the intervention had


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been successful in this particular subject and setting. It appears that the dramatic effect of the single, small intervention is mainly dependent on the pedagogical nature of the intervention and its appropriate application within the particular context of the chemistry teaching at this university. However, the fact that an event, which happened once only in a student’s experience, was able to turn achievement in organic chemistry around suggests that the actual structure of the subject cannot be ignored. The structure of organic chemistry has been described as linear with a clear organizing principle and it is this structure that made it possible for the intervention to have the impact that it had. It can be hypothesized that a single intervention, by an instructor with similar PCK, in a discipline with a branched structure, would not have had the same effect. The reason for this is that students would not have had so much to gain from grasping a single concept. However the pedagogical nature of the intervention underpins its success. We have shown that an intervention even in a linear discipline is not enough, unless it is driven by the enthusiasm and PCK (5, 6) of a particular person. Knowledge of the subject structure forms part of PCK. Despite the fact that the intervention was still in place in the same setting in 2000, there was less enthusiasm for it from teaching staff, mainly because of time constraints. We finally discussed the possibility that the intervention’s success is also attributable to the fact that an implicit goal of the teaching was to equip students for puzzle-solving that characterizes NSE. The understanding of the strategies necessary to accomplish organic puzzle-solving is also part of the PCK of the instructor. Literature Cited 1. Huddle, P. A. J. Chem. Educ. 2000, 77, 1154–1157. 2. Green, V. G. Student Adjustment to Second Year University Level Chemistry—A Study of the Second Year Experience. Ph.D. Thesis, University of the Witwatersrand, Johannesburg, South Africa, 2002. 3. Taagepera, M.; Noori, S. J. Chem. Educ. 2000, 77, 1224–1229. 4. Jensen, W. B. J. Chem. Educ. 1998, 75, 679–687. 5. Wilson S. M.; Shulman, L. S.; Richert, A. E. “150 Different Ways” of Knowing: Representations of Knowledge in Teaching. In Exploring Teacher Thinking; Calderhead, J., Ed.; Holt, Rinehart and Winston: Sussex, United Kingdom, 1987; pp 104–124. 6. Shulman, L. S. Educ. Res. 1986, 15, 4–14.

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7. Van Berkel, B.; De Vos, W.; Verdonk, A. H.; Pilot, A. Sci. Educ. 2000, 9, 123–159. 8. Caldin, E. F. HYLE 2002, 8, 103–121. http://www.hyle.org/ (accessed May 2006). 9. Erduran, S.; Scerri, E. The Nature of Chemical Knowledge and Chemical Education. In Chemical Education: Towards Research-Based Practice; Gilbert, J. K., de Jong, O., Justi, R., Treagust, D. F., van Driel, J. H., Eds.; Kluwer: Dordrecht, The Netherlands, 2003; pp 7–27. 10. De Vos, W.; van Berkel, B.; Verdonk, A. H. J. Chem. Educ. 1994, 71, 743–746. 11. Gabel, D. J. Chem. Educ. 1999, 76, 548–554. 12. Chen, A.; Ennis, C. D. Teaching Teach. Educ. 1995, 11, 389– 401. 13. Ball, D. L.; Bass, H.; Hill, H. C. Knowing and Using Mathematical Knowledge in Teaching and Learning: Learning What Matters. In Proceedings of 12th Annual Conference of Southern African Association for Research in Mathematics, Science and Technology Education, Cape Town, Jan. 13–16, 2004. http:// www.phy.uct.ac.za/SAARMSTE2004/ (accessed May 2006). 14. Orgill, M.; Bodner, G. Chem. Educ. Res. Practice 2004, 5, 15– 32. 15. Nilsson M. R. J. Chem. Educ. 2001, 78, 628. 16. Kuhn, T. S. The Structure of Scientific Revolutions, 2nd ed.; Chicago University Press: Chicago, 1970. 17. Zoller, U. J. Chem. Educ. 1993, 70, 195–197. 18. Robinson, W. R. J. Chem. Educ. 2001, 78, 20–21. 19. Pintrich, P. R. Theory into Practice. 2002, 4, Autumn, 219– 225. 20. Clouston, L. L.; Kleinman, M. H. Can. Chem. News 1998, 50, 15. 21. Taxonomy of Educational Objectives. Handbook I: Cognitive Domain; Bloom, B. S., Ed.; David McKay: New York, 1956. 22. Zoller, U.; Dori, Y. J.; Lubezky, A. Int. J. Sci. Educ. 2002, 24, 185–203. 23. Green, G.; Rollnick, M. Cognitive Demand and Testing Practices in Tertiary Education—A Study of First and Second Year Chemistry Examinations. In Proceedings of 11th annual meeting of Southern African Association of Research in Mathematics, Science and Technology Education. University of Swaziland, Waterford, Kamhlamba, Swaziland, Jan 11–15, 2003; pp 33– 39. 24. Felder, R. M.; Brent, R. Chem. Eng. Educ. 2002, Summer, 204–205. 25. Bernstein, B. Pedagogy, Symbolic Control and Identity; Taylor and Francis: London, 1996. 26. Zoller, U. J. Res. Sic. Teach. 1990, 27, 1053–1065.


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