Understanding, Mastery-Active Learning, and HYPERCHEM : Experiments with MO Theory K. R. Fountain and Brian R. McGuire honneasl Mlsso~rSlate Ln versllf Knrkswlle, MO 63501 Active learning (1)and mastery learning (2)both hold out the promise of increased effectiveness in the learning process. Both learning models are based on some degree of cooperation in the learning processes. Active learning literature expresses the necessity of engaging the learner's emotional base (3). This desirable feature is reported also in many other places (4).Novak reported that "Educative value is experienced when we recognize t h a t we have grasped a new meaning and feel the emotion that accomnanies this realization" (5).A v e compact ~ wav of exmessing this emotional support for a learned concept is the term "endocharm" (6). The synthesis of active learning and mastery learning reported in this paper combines features of both deeply related schemes of learning. The method of combination is to include the formative material, typical of mastery learning, with group learning experiences, typical of active learning, in a highly visually appealing, quantitative presentation available with modern, graphical user interfaced (GUI) programs such a s the PC-based HYPERCHEM or the Mac based CaCHE. The combination of sound, interactive materials in this process seems to overcome problems nreviouslv encountered with d e ~ e n d i-n eon the comDuter for teaching. Such a problem is illustrated in the next section. Other examples of using the computer a s a classroom vehicle for learning include the experimental course reported by Casanova and Casanova (7).I n the cited work the important point was made that: The mere oresentation of imaees in the classroom may not promote student ability to reason with images, and worse, it may impede the development of such abilities by reducing the need for students to create their own abstractions
The most important finding reported in this citation was that students who used the computer a s a replacement for the chalkboard failed to take notes, reported a n enhanced sense of learning from the increased visualization but did very poorly on standard examinations over the material (the "Feynman effect"). The introduction of a more active participation in the second quarter, when a synopsis of what the students saw and heard was required, produced much enhanced scores on examinations. The experiment described in the present paper represents a step in overcoming the pitfall attending the Casanova experience because in both a prelab (Formative) period and a postlab (Summative) period strong interaction between the concepts and their expres. presented . sion is required. The strong favorable emotional response, renorted bv Casanova. is retained in the present e x ~ e r i ence. Such a n emotional support is necessary for deepseated integration of conceptH -with the learner's cognitive structure. as renorted bv active learning literature (1). I n the next section this emotional support is described and linked with previously reported concepts in chemical education.
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Journal of Chemical Education
Mastery and Endocharm Skill learning, as pointed out by Novak, involves messages from our muscles, together with externally derived information (3).The result is that internally derived signals of pleasure occur when a skill is mastered. This internal simal has been called "endocharm" (6). ~ndoch- is similar to mastery, but is more emotionally based. I t involves mastery in the sense that it too is a release ofexistential tmsion in\&ed insolvinga prohlem Additionall\: it undeniably invol\.esa litt~naofthe solution ofthe proh l e i into one's existent intellectuai framework. A profitable analogy for understanding endocharm Exocharm is comes from contrasting it with exocharm (8). the charm exuded by a good chemical demonstration. One of the most exocharmic demonstrations is the demonstration of chemical explosives in a fireworks display. A brilliant green flourish a t the end of a display brings OOhs and Ahhs from the crowd. They, thus, experience great exocharm. Somewhere in the crowd a small bov savs to himself. "Why was it green?" He has absorbed the egocharm of the demonstration, putting himself into a state of intellectual tension. Only exocharm so absorbed can lead to endocharm. Later in his home chemistry. lab,. with a platinum wire resurrected from a waste crock a t a local college Freshman chemistry lab, and lovingly cleaned with hot nitric acid, he discovers that all copper salts and barium salts give off the same green flame that he saw a t the fireworks. He forms the hypothesis that there must be barium or copper nitrates in the powder of the fireworks. When he so informs his friends thev are amazed that he knows this. So are some adults. In f a d , he finds that he can even argue with his teachers about the com~ositionof fireworks. This powerful connection of events gives him a certain emotional lift that he never had before, endocharm.This resulting feeling of understanding, of fitting together something in the environment into a n understanding - framework, is endocharm. The Need for Concrete Presentations Piaget has taught that a recapitulation model occurs in many instances of learning (9).This means that one seeks a more concrete presentation in a new learning situation before the abstract meaning of the lesson is grasped. Certainlv no more abstract c o n c e ~exists t in either general or organic chemistry curricula than the way molecular orbitals (MO's) are constructed from basis set atomic orbitals. Certainly no area of the curriculum could be better served with concrete experiments presenting the way of things in diatomic molecules. A progression across the periodic table, showing how each diatomic system builds itself is standard fare for most general chemistry books (10).Perhaps no subject in the general chemistry curriculum suffers more from a lack of concrete experiences. Indeed, in the author's experience, lack of the ability to grasp this concept causes untold grief in the next course, organic chemistry, and contributes more to dropout rates in that course than any other factor. Such GUI-based (graphical use interface) programs as HYPERCHEM' or Cache have features that allow develonment of concrete, quantitative experiments to prt.wnt rhr concems of the lbrmationi of the diatomic MO's of the t>lumenti of the first row of the periodic table. The following sections Dresent MO-bonding schemes develo~edbv using -
HYPEREHEM.
Experimental MO Theory Desired features of a first MO-theory experiment iuclude: 1. Quantitative relationships between the orbital energy levels. This would allow far students the concrete experi-
a
s
ah
The HYPERCHEM MO's of the H-H molecule as a functionof r. enee of generating their awn orbital-splitting diagrams from MO e n e r ~ edis~laved s on the screen: 2. Qualitative e&uati;n i f the shapes of the MO's. This would entail pictures of the MO's corresponding ta the energy levels in (a); 3. Connecting these MO's, once generated, with the events occurring at asymptotic solutions (zero overlap) at large internuclear distances; 4. Provide a reasonable way ta generate the Morse potential, connecting it with the MO's at each point on the Morse curve. These features. if oresented in a concrete wav would disoel much of the rote memory of the MO presentation in mist eeneral chemistni textbooks. HYF'ERCHEM allows all of These features t o b e presented in a series of short quantitative experiments. HYPERCHEM also presents the advantage of running on a 386-based PC under WINDOWS enabling teachers a t modestly endowed high schools to employ it. These experiments are suitable for use in high school advanced chemistry courses, general chemistry, organic chemistry, and physical chemistry. In both Organic I and Physical chemistry courses this experiment has led to greater student acceptance of MO theory and better performance on exams. Although HYF'ERCHEM supplies many advanced features, the present series of experiments requires nothing more than a pencil, sheet of paper and the ability to manipulate a mouse. This gives a "high touch" ( 4 ) feeling to the obvious "high tech" nature of HYPERCHEM and quantum mechanics, in general. Plotting the numbers generated can be done on spreadsheets, such as Microsoft EXCEL 4, or graph paper. Experiment Formation of the H-H Bond The experiment begins with a formative period where base groups from the lecture or lab (1, 6 ) complete formative material. These base groups are students who have committed themselves to each other and to learning actively. The best results are achieved when a performance bonus is given to each member of a group that achieves a
preset score on any given learning task. Because this experiment is extensive and involves the bringing together of the efforts of several groups, we suggest a substantial performance bonus with liberal terms (I). The formative material consists of terms they will need to use in their postlab write-ups. They are given a scaled version of the Morse equation and asked to calculate energy values from it for the formation of the Hz molecule. (They make a data table and, a t NMSU, use Slidewrite to make the plot.) This process also can be done a t a high school level with paper and pencil. From their plot they discuss the process of minimization of energy in their groups. The next prelab project is to discuss the reading in the textbook on molecular orbital theory in terms of symmetry classification. The formative material guides them to classify symmetry in terms of two simple operations on the molecule, looking down the internuclear axis, and looking a t the molecule a t 90 from the internuclear axis. The third group discussion centers on how the symmetry is related to bonding and anti-bonding MO's. Finally, each group is assikmed a different research proiert consisting ol'a different homonuclt,ar or heteronuclear diatomic mol&le. Each group calculates their molecule as described below for the H-H molecule. Different roles are played by each group (of 3-4 students) a s pointed out by Johnson, Johnson and Smith (1). Because the sequence of computations for each molecule is the same, but involves many single point calculations everyone gets a chance to use the computer. Pictures of the orbitals may be printed out, a s they are generated, for each point along the Morse ~ o t e n t i a lcurve. Finallv. the molecule's eeometni is minik e d , by proper rhoice of options, u s i n i t h e &l Hamiltonian. The eauilibrium valut,.i fir the enerm and the inter nuclear distances are always noted so one-gets a smooth discussion of the minimized values with the single point computations. An example of the plot obtained is the figure for the Hz molecule. Post lab discussion consists of classifying the MO's for the minimized structure a s bonding or anti-bonding, constructing the MO-splitting diagrams from the actual MO Volume 71
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energies supplied by HYPERCHEM, and construction of the Morse potential. A discussion of the connection of the bonding of the truly minimized molecule i n terms of the Morse potential and the bonding energies of the MO's generated by the single-point computations is required. Several operations will be needed. The actual sequence of items needed for each operation is summarized in a TOOL BOX sheet given to students a t the first of the experiment (available on request). This experiment illustrates the features of HYPERCHEM necessaw to perform all of the diatomics in our lab experiment. A full copy of the laboratory experience i s available on request from the authors. Student reception of this kind of experiment shows that they achieve a meat deal of endocharm as they see the actual quantum-theory i n a concrete form. Students i n higher level classes, such a s organic chemistry have remarked to the author: "If only I had been taught this way I'd now be a chemistry major." I n fact much soul searching i s eoine on amone those who could still change their majors. This concrete expos6 of a subject that has the reputation of being arcane for students, and one that is seemingly unappreciated even where it is used repeatedly, i.e., in oreanic chemistni has both the elements of masteri and en., docharm Students exposed to thls experiment always np. Dreclate what :in M O actuallv is. Manv mvr rxprcsslons of kelight in understanding so concreteiy what goes into making a n MO, and why i t is important to know this. Typi-
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cal students display the subsequent change in quality of auestions disolaved bv those students described in our ore;iously reported: article defining endocharm (61, nakely, thev . beein to eive out more information in askine- a oues. tion than they are seeking in the question's answer.
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Acknowledgment We thank the administration of NMSU for the purchase of a Gateway 2000 4DX2-66 MHz computer for the development of this experiment. We also thank AutoDesk for a gift copy of HYPERCHEM that was used i n this development. Literature Cited 1. Johnson. D. W.: Johnson, R. T ; Smith, K A. A a i w h o r n i n s Cmpemfion in t h Coilem Clossrmm: Interaction Book Co.: Edins, MN, Chapters 3 & 4. Mostary Lpamiig; Wadsworth:Belmont, CA, 1985. 2. ~uskes-T.R. Impl~m~nfing 3. See, far erample, the role of the affective learning in cognitive learning schemes in Novak. J.D A Tkmry ofEdurntion: Cornell Universityhess: lthaca, NY.1977, pp 2 6 2 8 , especially Fig. 1.1. 4. Nai~hitt,JMegntrsnds: lk" N U Dimlions 'Pansforming our Lines; Warner Bwks: New York, 1982. Chapter 2. 5. Novak. J. D.: Gob. D. Bob. hornin* Holu to Learn: Cambridee Universitv Rosa: N& ~ o r k :1984, pp 17-19. 6. Afial, D.:Delaware, D. L.; Fountain.K R.J. Ckem. Edue. 1990.67,1011. 7. Casanova.. J.: Casanova. S. L. EDUCOMSorine 1991.31. 8. Ramette,R. W. J. Chem. Educ 1980.57.68. 9. Phillips, J. L., Jr. ThOtiginsdInLikef:P~og~t'sTh~ory. 2nd ed. W. H.Freeman: San Francism.1975, p 171. 10. Um1and.J. B. DenemlChemislry 1895,pp 373378; Zumdahl, S. S. Ckomistn. 1989, pp 396404: OxLobs D. W..: Nachirieh, N. H. Principles ofModern Chemistry. Chapter 15; Petrucci, R. H.; H a m o d . J. J. General Chemistry. 6th ed.: pp 41%
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