Using Research in Chemical Education to lmprove My Tea~hing J. Dudley Herron Purdue University. West Lafayette, IN 47907 Research in psychology and education can tell us no more about how to teach chemistry than research in chemistry can tell Du Pont how to manufacture and market a new product. I t is my hope, however, that i t will tell us no less. In hoth instances we are dealing with complex activities influenced by many variables, some of which are beyond our control. When we develop curriculum materials and implement them in the chemistry classroom we make management decisions, weighing evidence from many sources and making compromises that we judge appropriate under a given set of circumstances. All too often we make those decisions without considering what is known about learnine, motivation, and other factors that clearly affect education in a school setting. I want t o examine in this paper how information from psychological and education research might influence these decisions by discussing how I have tried to implement this information in the remedial chemistry course I teach at Purdue. My discussion will focus on a particular view of the learning process based on research in cognitive science, rather than the individual research studies. Goals of Education What we do in education is influenced by what we think, what our students think, and what the general public thinks are the goals of education. For me The goal of education in the United States, or any other technologically-based,demoeratic society, must be to produce autonomous individuals who are capable of acquiring information on their own, judging the validity of the information acquired, and making reasonable inferences based on that information. By reasonable, I mean inferencesthat appear to be consistent with the information at hand and with previously made inferences. Education, then, is aimed at making students independent. Part of what makes us inde~endentis information. Yet. if there is a conflict between acquiring infmnation and lenrning hou I,, acquire information, precedence must he given to the la~rer. ~~
~
How We Learn Those influenced hy the work of Piaget ( I ) have usually focused on his descri~tionof intellectual develo~mentthroueh a series of stages. As important as that work h& been, the idia that has had the moat profound influence among psychologists is Piaget's constructivist view of intelligence. Essentially what Pianet said, and what a mowinn number of develoomental psychologists have come i o accept, is that all of us cbnstruct knowledge within our own heads. In other words, knowledge is never transmitted intact, from one individual to another. Instead, each of us receives some signal . from the environment through one of our sensory organs, and that signal is then interpreted according to some "schema" or pattern that we have previously built, and then incorporated in modified form as new knowledge. From birth, we acquire information and use it to build intelligence. The intelligence that we huild is then used to process new information and build additional intelligence. This process, summarized in Figure 1, continues throughout life. If we think of the information impinging upon us as being 850
Journal of Chemical Education
HIGHER-LEVEL ABSTRACTIONS
OEEf
EVEL
t
THEORETICAL FRAMEWORKS. VALUES AND BELIEFS A
I INFERENCES BASED ON INFERENCES
t
INFERENCES BASED ON OBSERVATION
DIRECT SENSORY PERCEPTION
t SURFA Figure 1. Stages in the development of knowledge, from structures.
LEVEL
surface to deep
a t the "surface." then we see that knowledee develons from this surface level to increasinglymore compl&, intercokeded structures that mav he thoueht of as meaninful or "deen" structures. ~ r o c e s i i ninformation ~ that is close to dir& sensory perception may he thought of as "surface-level processing" and processing information in terms of increasing complex levels of meaning would be "deep-level processing." We need t o keep in mind that hoth kinds of processing go on a t all times. One kind of process starts with the external stimulus and proceeds upward towards deeper levels of meaning. This is called "bottom-up" processing. At the same time, however, the knowledge in our head that is accessed a t the time the external stimulus was perceived is working in the other direction t o impose a particular meaning on the perceptual skills. This is called "top-down" processing. Optical illusions are one example of top-down processing. Another example is the use of contextual cues to process language. If you hear someone say, "I want t o buy an apple," while shopping a t the grocery, you immediately know what the individual is looking for. If you hear the same phrase in a computer store, however, you come to a totally different conclusion. Our knowledge of what goods are sold in a particular store, coupled with our knowledge that two very different things are called "apples," forces us to impose different meanings on the same stimulus. The meaning comes from a combination of bottom-up and top-down processing. From the bottom up, we process the sound and access the word apple; from the top down, we infer what apple should mean in a narticular context. 1suggest levels of information, or a data base, to use comouter terminoloev. I t is imnortant to realize that we are also building knowlidge about'how to huild and manipulate knowledge; a library of utility and applications programs, if you will. Examples of this process are given in Figure 2.
re
HIGHER-LEVEL ABSTRACTIONS VALUES. BELIEFS ATTITUDES. EMOTIONS MANAGERIAL STRATEGIES ..-.--.--.-.-.-..--.-FORMAL OPERATIONAL SCHEMAS CONCRETE OPERATIONAL SCHEMAS SENSORY MOTOR SCHEMAS
ENVIRONMENTAL STIMULI Figure 2. Knowledge about how to build knowledge.
HIGHER LEVEL ABSTRACTIONS THEORETICAL FRAMEWORKS. VALUES AND BELIEFS
,
-
INFERENCES BASED ON INFERENCES u
FORMAL OPERATIONAL SCHEMAS INFERENCES BASED ON OBSERVATION CONCRETE OPERATIONAL SCHEMAS DIRECT SENSORY PERCEPTION SENSORY MOTOR SCHEMAS
ENVIRONMENTAL STIMULI
I have separated the schemas at the bottom of Figure 2 from those a t the top because I am not sure that they act in the same way. If we juxtapose the information from Figures 1and 2 to form Figure 3, we readily see the relationship between the items a t the bottom. But the relationship at the top is less obvious. T o summarize, we build knowledge from the time we are born until we die. This buildine nrocess is influenced bv the information that impinges on our senses, but i t is guided by the eeneralized knowledee that we have alreadv constructed. It isour facility with gen&ized knowledge thaLis interpreted as intellieence. and i t is the develonment of such intellieence " that is t c e g o i of education.
-
L
Prevailing Vlew of Learning The view of learnine iust outlined emnhasizes that knowledge is constructed by each learner within his or her own head. It is not transmitted, intact from one head to another. In other words, teaching is not telling,even though we tend to behave as though it is. Why do we behave this wav? There are manv reasons. First, andforemost, we know very well that we do learn a meat deal when we are simplv told. Even now, I assume that you are acquiring information because I am telling you something. But thereareconditions. For one, I am writinr! in English i d you have previously built an elaborate framework of information concerning proper and improper inferences t o draw when you read. ~urthermore,you have a storehouse of knowledge about teaching and learning that provides a framework within which vou urn incornorate the ideas behind my words. Because of that, you can learn from reading or listening, and I can teach by writing or telling. When new information fits neatly within an existing framework or schema, we can absorb a great deal of information with little effort. At any point in time, a great deal of leamine is of this kind. Occasionallv. the new information d m not q u s e fit, but, by adjusting our ideas slightly, we are able to incorporate the new data. However, if the schema of the "learner" is very different from that of the teacher, little is taueht bv telline or what is learned-i.e.. constructed in the miid of the & d e n t i s very differkt from what is taughtconstructed in the mind of the teacher. There is a large and growing body of research aimed a t discoverine how science students a t various levels view the world, and;t is best summarized by noting that our students have a verv different view of the world from our own! Because of this, we often have difficulty conveying our view of the world by telling. Shin from Telling How I Think to Learning How They Think The major influence that research in psychology and education has had on mv teachinr! is the portion of time I spend telling students what1 think v&us the portion I spend &king them what they think. Although my class is organized rather conventionally (two lectures and one 3-hr lab per week), I have altered what I do in both lecture and lab. Even in large lecture sections, I ask my students to generate what they consider to be a sensible solution to problems or a sensible interpretation of events. A single example must suffice to illustrate this process.
Figure 3. Levels of knowledge compared to the operational knowledge used to build It. We view several reactions in solution and discuss stoichiometric calculations involving those reactions before I introduce concentrations of solutions. I may, for example, mix a solution of Ph(NO&and a solution of KI and have students calculate the numbers of moles of Pb12 that could form from a specified amount of reactants, based on the equation,
I then place bottles of the solid reagents on the lecture bench alongside the solutions we used in the demonstration and call attention t o the fact that the information used in the calculations was the amount of the solid reactant, but the demonstration used the reactant mixed with water.1 tell my students that we have a practical problem: I need a way to describe the solution so that I know how much of the "active ingredient'' is present when I pour out a sample of the solution. I then ask them, "How can I describe these solutions?" Students make suggestions and I encourage others to evaluate them. We consider thines like weieht nercent and realize that such a description would work,lbut'it would require us to weigh the solution rather than measure its volume, which is a simpler procedure. This often leads t o the suggestion that we describe the mass of solute in each milliliter (or liter) of solution, and that is accepted as another suitable description hut one that requires a subsequent conversion to moles of solute in order to use chemical equations for stoichiometric calculations. Eventually, a description in terms of the moles of solute dissolved in each milliliter (or liter) of solution is accepted as a particularly useful description in view of the calculations we have been doing, and a formal definition of molarity is then presented. This kind of development takes considerably longer than simply starting with a straightforward definition of molarity from the heginning. How can I justify this waste of time? I do so on the following grounds: 1) It insures that the development of the idea-eb 2)
3)
4)
5) 6)
conception that is sensible to the students. It is, after all, their suggestions that we start with. It insures a step-by-step eonstmetion of the concept from an idea that is alreadv sensihle to the student to the idea that is most sensible to me. It insures that the student has an oooortunitv to learn whv .. chemists have adopted this way 10 express concentration and have rejected others that, t u the h~inningstudent, may appear preferable. Chemical knowledge is seen as the product of rational thought to achieve particular ends in an efficient manner rather than arbitrary rules to be accepted on the basis of authority. It provides an opportunity to see the utility of,and to practice, several of the general intellectual skills that we use to construct useful knowledge. The resulting concept is more likely to be meaningful to the students.
Something similar often takes place during lab. The instrudor engages either individuals or groups of students in a dialog Volume 61 Number 10 October 1964
85 1
about the meaning of the laboratory activity. Iwill illustrate this dialog with an example from a recent discussion with a student who was conducting a n experiment that used paper chromatography to separate the dyes in ink.
T (Teacher): How's the experiment going? S (Student): Just fine. T (looking at chromatography paper in the beaker and calling attention to a varticular dot): Whv is this ink sevaratine into the different cb~ors? S: Well, the solvent is causing the ink to decompose. T: Let me see if l understand what you mean by demmpme. When chcmisrs use this term, they mean something like what happens when you do an electrolysis of water (discussed in a previous lecture). Electric current is passed through the water and the water actually breaks apart into hydrogen gas and oxygen gas, components that are very different from what you had in the beeinnine. Is this what vou think is takine dace in the ink? 5: w&, uh,-1'm not sure. T: What else might be taking place here? S: Well, I guess the solvent could he-well, like filtering out things. T: Can you tell me a little better what you mean by filtering out? S: Well. kind of decomnmine into narta. T: Let &e describe two &&and &e if I can heln vou aart outtwo possibilities. I can take peanuts, cereal, and pretzels and make a party mlx. I can then take the party mix and separate it Into components by picking out the peanuts and putting them in one pile, picking out the cereal and putting that in another pile, and so on. Chemists would say that the party mix represents a mirture and that we are simply separating the mixture into components. Chemists contrast that with the other process I described a minute am. decomomition. Chemists think the two processes are fundamentally different. In derompos~tion,you have one kind oisubstance that breaksapart intocomponents that have very different properties-so different that you wouldn't dare call them the same as the original substance.For example, water certainly looks nothing like the oxygen gas in air, and neither does it behave in the same way. If you don't believe this. dive into a swimmine ..owl and trv to hreathe the wat~r!You ran, huwever, breathe the oxygen produced when water break apan. That's dffermt from the separation of the party mix. If you put a handful of party mix in your mouth, you will taste the peanuts, the cereal, and so an. Although the sensation is not quite the same as eating a handful of peanuts, and then a handful of cereal separately, you have no difficulty concluding that the tastes are the same, just mingled together, rather than totallv different tastes. In other words. in the uartv mix, it seems thaithe propenies are there hut all mixed up and you separate them: in the water situation you literally pnxluce numething with n ~ w properties. Now, after that long explanation, can you tell me wh~chof these two things is taking place on thechromatography paper? S: Well, I really think it's more like the pany mix situation. T: You're rieht. that is what we believe is haooenine. Now let me forus on &&thing else. (Points u, a dot on ihe ch;omatogram.) I see that there is a yellow dot right at the bottom of paper. where you put this ink and it started to separate. Over here is another yellow dot at the bottom. In fact, there are 3 or 4 inks which seem to have a yellow dot at about the same height ahove the line. How do YOU intemret that information? What is that telling you about the different inks that were placed on that line? 8: 1don't know. That they break down into the same things? T: What do you mean by "break-down"? Rememher, that's the term a chemist would use to describe what happens to water, hut not what happens to the party mix. S: Well, they separate. T: All right, what does that say about the components of these various inks? Do they have anything in common? 5: Well, I guess you'd have to conclude that these inks all have some yellow dye in it that's the same. T: That's corre&and why do we make that conclusion? S: Well, they are both yellow. T: That's right, and what that says is that there is a property of these substances that is the same which leads ua to believe the substances are the same. Is there any other property of that dye, other than being yellow, that appears to he common?
".
..
.. .
~
~
.
. .
852
Journal of Chemical Education
9: Well, I don't see anything. T: AU right, let me focusyaw attention on something else. Besides this vellow color down here near the hottom. notice on this other ink,ihere9sa color way up on the paper. ~1;eculorslouk pretty much rhesame. Are these the same dyes? In other words, is the yellow up here near the Impof t h p paper thesame as that yellow down at the bottom? S: Well, I don't think so. T: Why not? S: One of them went up to the top and the other one stayed down here at the hottom. T: Exactly riyht. In other words, what you'resayingis that those twu yellow dyes have a different property. They aren't moved along at the same rate by thesolvent. According w the rules of the game that chemists play, we say that if all of the characteristic properties of the two dyes are the same, they are the same suhstance. If these properties are not the same, we a s s v e they must be different substances. Now you have to worry a little bit about what's acharaeteristic property and what isn't, hut I will simply tell you that the rate at which things move along this sheet is a characteristic property. Therefore,that property can he used to identify the suhstance. S: I see. That makes sense. T: wio, give this some thought as you're thinking about theesperimtnt and interprting your results. Looks like you're getting good results. ~~~
~~
~
~
~~~~~~~~
Textbook Selection One of the most important educational decisions we make is the selection of a text. My first concern is whether the chemistry is correct; my second is whether the text facilitates learning. According t o my understanding of learning, when my goal as a chemist is to develop higher level abstractions, as i t often is, I can facilitate learning by starting with those things that are closest t o the students' direct experience and then develop ideas sequentially from that experience to the theoretical framework I ultimately want to reach. Thus, I l w k for a text that begins with chemistry that students can observe and builds to the theory that allows us to rationalize this behavior. Most texts, unfortunately, do the opposite, beginning with atomic theory and ending up with descriptive chemistry. I therefore ended up wiring my own text ( 2 ) . I do not want to suggest that we either can or should build every item from the ground up. Students have already made inferences and established values and theoretical frameworks before we see them. We can and should make assumptions about what students already understand and build on it. But when we make those assumptions, we must make connections between what we are doing and what is understood. There are those who argue that we have two choices when faced with teaching a subtle concept, such as heat capacity: (1)we can either "do i t right," which means developing the idea the way we plan tn use~inphysical chemistry, or ( 2 ) we can ignore it completely. Their concern is that the kind of lying that we do in introductorv courses often interferes with learning more powerful ideas later on because students construct schemas that thev continue to use in later courses.When students encounter complicated problems in physical chemistry, for example, they try to use the schemas developed as freshmen or sophomores, and fail. This is OK, if that failure leads them to an understandint! of whv the schema was inadequate and how it can he modified tomake it work. It is not OK, if the existinaschema must be tntallv discarded and a new one built to take its place. This is t h e problem we face in freshmen chemistry when students come to us "knowing" that electrons circle nuclei in fixed orbits, and we try to teach the quantum mechanical view of the atom. There is no simple fix for the old structure; instead, you have t o tear it down and start over. What can we do? T h e answer, I believe, is to do what a homebuilder on a limited budget does. He builds a part of the house, but plans the building so little reconstruction is needed in order to add extra rooms later on.
How Did I Base Educational Declslons about My Course on Research In Cognltlve Sclence?
1)I looked for a text that began with direct experiences that could be understood using the logic that I know beginning students bring to the course and I found none. All I could find were texts that told what to do to get right answers with little or no hint ahout why the procedures would work. I therefore wrote a text. 2) I tried to schedule the class in a laboratory where students could come to investigate questions raised in their own mind, discuss their ideas about what they observed with other students and staff, and move along in the course at arate that was reasonable for them. This could not be done. so I com, promised. I scheduled lab for everyone on ~ o n d a iplanned experiments that could be completed and discussed during the lab, collected data from some labs for discussion in lecture, and planned demonstrations to complement the laboratory exercises, presenting these demonstrations with questions and discussion as described earlier. 3) I set standards for my remedial chemistry course based on the assumption that the purpose of my course is to develop the thought patterns used in chemistry to show how those thought patterns can be used to understand the physical world and otherwise prepare students for a general chemistry course a t the college level. Students who demonstrate that understanding pass the course, those who do not fail, regardless of effort. The goal of education is to construct knowledge that will enable us to act as independent learners, and I hope that is what mv erades reflect. 4) My tkxi incorporates questions that should reveal to the student how well the material presented in the previous section is understood. The only homework assignment is to answer those auestions, check the answers, and ask for help when they do noiunderst'and. 5 ) There is a short quiz each week over the previous week's work. Students who score 80% or above are told that they have understood and pass; students who score below 80% are told that they have not understood and fail. T o the extent that it is practical, they are told what they do not understand, and are given suggestions for further study. If they wish to receive credit for the quiz, they may retake the quiz within a week, up to a maximum of two repeats. There are also three 1-hrexams and a final exam; together they constitute 75% of the course erade. 6) A conscientious effort is made to ask questions on both auizzes and hour exams that will reveal what we have found be common misconceptions or skill deficiencies. Many of these auestions seem trivial or common~lace.but I will share a few&st the same.
fying and remediating the cause of failure. Here are the steps: a) I begin by asking the student if he or she knows why performance is poor. In a large number of cases, the student confesses that little effort was devoted to studying and that correction of that should change results. After first assuring that the students know (or helieve they know) what needs to be done to improve learning, I terminate the interview. h) If students indicate that they are making a reasonable effort, I seek information ahout how they use their time and the resources available for learning; e.g., text, problem assignments, laboratory assignments, repeated quiz procedure, the Resource Room, and tutorial help. In the case of college freshmen,it is common to fmd that students have made unrealistic assumptions concerning the time needed to learn, manage their time poorly, are unaware of available help or fail tn use it, and are committed to more work and comes than they can complete. On the hasis of information received from the student, I counsel the student toward more realistic manaeement of " time and resources. The counseling is made as specific as possible; for example, instead of suggesting that the student utilize wasted time between scheduled classes, I work with the student to develop a realistic schedule that includes specific study commitments as well as class assignments. c) Once it appears that students are utilizing good study habits hut are still failing, an appointment is arranged for content analvsis. This analysis focuses ontist questions and the student's errorpatterns. My analysis takes several forms. First, a grca analysis is made to see if the majority of items missed are lower-level, recall items, higherlevel questions that require analysis and synthesis of information, or a combination.Students who do well on complex items that require analytical thought hut miss knowledge-level items (a surprisingly frequent situation) are counseled that some essential information must be memorized. If needed, specific suggestions are made for memorizing such knowledge (3). Some error patterns suggest that difficulties are tied to specific concepts or skills, e.g., the student may miss several questions in-
-
tb
Whirh of the followinguniu, should be used toexpress the mass of an object? (a) &Tamlb) millilitpr (c) meter (d) rm3 (e) more than
Figure 4. In each of these drawings, tha small, black circles represent atoms of a differentkind, and figures in which two or more circles touch represent molecules.
-.... . ...-. .
What irtheaumid(fi.02X INT 7 (3.01 X lo2')? (a)9.03X ll@(b) 9.03 X loz1 (~16.32X 102Vd)6.32 X lUJ?(e) 3.01 X 10' Whirh of th? drawings in Figure 1 represent a mixture? (a) 1 (b) 3 (c) 4 (d) 5 (e) both 1and-5 are mixtures Which of the drawings in Figure 4 represent a pure compound? (a) 1(b) . . 2 (cl4 . (dl . . 5 (e) . . both 4 and 5 are oure comoounds A student measured the maw and volume of ~everalglass rod? and used the data to plot the qaph in Figure 6. I.acer he measured a piece of broken window pane and found the volume to be 10.0 cm3and the mass to he 14.8 g. ~
(a) Is the piece of window pane made of the same kind of glass as the rods he used in plotting the graph? (h) How did you decide your answer to part A? (c) There are four data points on the graph which do not fall on the line. Why? (d) Calculate the density of the glass used to plot the graph.
7) After the first hour exam, I talk to each student who scored below 70%. I initiate a series of steps aimed a t identi-
Mass of glass rods in gram
Figure 5. A plot of lhe volume of the glass rods in cm3 versus the mass of the glass rods in grams. Volume 61
Number 10 October 1984
853
volving exponential numbers hut not miss similar questions with integer or decimal numbers. When such patterns are detected, the student is asked specific questions to assess his or her understanding of the offending concept or skill. d) The most common pattern in my course is for students to do well on questionsthat require rote memory, but poorly onquestions that require higher level reasoning. When this pattern is seen, I ask students to completethe Whimhey Analytical Skills Inventory (WAS11 (4),a test of analytical sk~llsthat does not require specialized knowledge of chemistry, and return for another appointment. In the second session, the WAS1 is analyzed in much the same manner that the chemistry test was previously analyzed todetect specif~c reasoning
-- -
,iofi,.ienoi.-* ..-. ..-.-. .
r, Although I know that several of my student- are p w r readers of technical writing, I have nor instituted diegnoatic procedurrs for readmr: hecau~eI have insufficient time tcr deal with the areas already described. Such a diagnostic procedure is needed
Concluslon How much of what I do is influenced by educational philosophy and how much is influenced by educational research is difficult to assess because they are so totally intertwined. Whatever the mix. I trv to base nrocedures on mv understanding of learning andempiricalkerification of edicational nractice. I have no assurance that mine is the best wav to teach but I think I know the basis for what I do. ~onse&ently, I believe I a m in a good position t o modify instruction in response t o new research on teaching and learning.
854
Journal of Chemical Education
Literature Cited (1) Some of the papers on Piaget'et'a stagtag of inteiledud development that haveappeared
inTms JOURN*L arelistedbelow.
Herron. J. D.."Piagct for Chemista:ErpkiningWhat'Gwd'Student.Can't Under. atand," J. CHEM. EDUC..52,115 (1975). Bciatel, D. W., "A Piagetian Approach to General Chemistry," J. CHEM. EDUC,52, l -. i l 1197CI . ,...-,.
Brwka. D. W., Aibanew, M., Dsv, V.W.. Koehlcr, R. A,, Lewis,J. D..Marianclli.R. J., Rack, E. P.. and Thomiinson-Keeay. C.. ,'Piagetian critecia as s Prediction of Suein First year Courses," J. CHEM.EDUC.. 53,571 (19751. Smith, P.J.,'"Pisget in High School Instruction." J. CHEM.EDUC.. 55,115 (1978). Henon. J. D., "Piaget in the Clasamom," J. CHEM. EDUC., 55,165 (1979).Goodstein,
-. ...,. .,...,... .,. G d . R . K m m h o u t , R A.,andMeilon, E. K., "Piaget's Workand ChcmicaiEducation," J. CHEM.EDUC., 66.426 (1979). Milakofsky, L., and Patterson. H. 0.. "Chemical Education and Piaget," J. CmM. EDUC.,56.87 (1979). Power, L. S.,"An Applicationof Pieget'sTheoryof CagnitiveDewlopment inTeaehing Chemistry: TheLeamingCycle," J.CmM. EouC..57.135 (1980). Bstt. R. H., "A Piagetian Learning Cycle far lntroductary Chemicsi Kinetics." J. CHEM.EDUC..57,634 (1980). Ryan, M. A,, Robinson. D.. and Garmiehacl. JW,Jr.. "A Piaget- B a d General Chemistry Lsborsmry Pmgram for Science Majors," J. CHEM. EDuc., 57, 642
(21 Huron, J. D.."Undc~d'mgChemisby:Ahe~toryCom."RandomHouae,N~
.-. .. ..
V".l-, I.#,
(3) Brsnsford. J. D., '"Human Comition: Learning, Understanding and Remembering: Wadsvorth Pvblkhing Co., Belmont, CA, 1979, pp. 5P85. (41 Whimhey, A,. and Loehhead. J.,"Pmblem Solvingand Comprehension," 3rd Edition, Tho Franklin InstitutaPress, Philadelphia. 1982.
