Concept Learning Theory and Design of College Chemistry Instruction Elizabeth Kean Chemistry Tutorial Program, University of Wisconsin-Madison. Among the first tasks of students who are beginning their study of chemistry is the learning of some basic chemical concepts. Students are expected to learn the svecialized vocabulary that is employedwhenever one "speaks chemistry." For example, at the bepinninr! of most chemistw courses, students &e introduced the words element and ~ & ~ o u n d . They may he taught that elements are substances that cannot be broken down into simpler substances by ordinary chemical means, whereas compounds can. Imagine the students' consternation when, after such an introduction, they are faced with this quiz problem: Identify from the following list those substanceswhich are elements and which are compounds: Na Hz He Ss CClq HF Students must somehow link the basis for classification of substances (the simplist/nonsimplist dichotomy) with the means for identifvine specific substances in each class (the chemical formul&hkh'describes the basic particle of a & stance). The student's ability to answer questions about these concepts will depend not only upon his or her background in chemistry, his or her ability to think and reason in abstract fields, but also on the quality of the concept teaching. Much is known from educational research about how students learn concepts and how to teach concepts effectively. The purpose of this paver is to vresent some asvects of concept ie&ning theoj(what conEepts are and how to analyze them), and to propose ways to improve the teaching of concepts in introductory ch&nistry~courses.Since tge usual method of teaching at the college (and occasionally high school) level is the lecture, this paper will emphasize that format, although many of the ideas presented are applicable to other instructional systems. Concept Learning Theory What Conceots Are
For purposes of this paper, a concept will he taken to he a set of specificobiects, svmhols. or events that mav. he .. erou~ed intu a class on t i e b& of sha'red attributes; tho set musi he referenced bv a class name ur svmhol ( I J. Crit~ralatrrrbutes of concepts are those relevant characteristics that determine class membership, i.e., whether or not an item is an example of the concept. Those characteristics that are irrelevant to concept membership are called variable attributes. In order for an~itemto hen member ofa concept class, it must possess all of the criticalattrihutrs belonging to that conrept. Conceots varv in dit'ficultv nccordine to a number of dimensions (2). lngeneral, concepts are ;ore difficult to learn as the number of critical and variable attrihutes increases, and as the attributes become more abstract and subtle. Most concevts that are taueht in formal schooline have more than onecritical attribute. A concept may have ;single set of such critical attributes. However, some concepts have more than one set of critical attributes, either (or all) of which may be used to determine class membership. For example, acids and bases may be taught from Arrhenius, BrBnstedLowry, or Lewis standpoints. Even more complicated cases 956
Journal of Chemical Education
Madison, WI 53706 of relationships among concept attributes exist (for example, the classification of formic acid u~ an organic acid rather than as an aldehvde). Concepts with more than one set of attrihutes, or with relationshiis among attributes are more difficult to learn than those with a sinele set of attributes. It is also useful to classif; concepts according to their hierarchical relationships to other concepts, since rarely are isolated concepts taught in chemistry courses. Some concepts are more fundamental than others. Some related concepts hear a coordinate relationship to one another, having approximately the same level of complexity. To illustrate these relationships, consider the following concepts. Carbonyl, a class of organic compounds which contain the
group, is a more fundamental concept than ester, carbozylic acid. amide. and so on. The latter concepts have a coordinate often form relationship to one another. ~oordinat~concepts mutually exclusive sets, i.e., members of one class are nonmembers of coordinate classes. Concept Learning The critical skill in concept learnina is that of classification. Such classificatinns require;hat students be ahle to generalize membership to all memhers of the set. Students also must be ahle to discriminate between members and nonmembers of the set. For example, to have learned the concept of ester would require that all esters could be identified as such by established criteria, and that a!.l non-esters he excluded from that classification. Examples of the concept serve the generalizing function while nonexamples emphasize the discriminating function. Ideally, students should be presented with sufficient examples and nonexamoles to illustrate each variable and critical attribute. Students at the hieh school and colleee level are exoected to learn concepts meaningfully and not simply to learn to ~ a r r odefinitions r for chemical words (3.4). Thev are exoected io recognize the relationship of a concept tobther related concepts and to extend the use of the concept to problemsolving situations. They may also be required to determine the critical and variable attrihutes of a concept without exnlicit teaching ~ ~ ~ ~ - - ~ - ~ Students g a y use many and varied strategies when they learn concepts. Some students are ahle to reco&ize intuitively from exposure to a few examples what the essential characteristics of a concept are. Others may need to first make a guess as to what the distinguishing characteristics might be, as tbev encounter new examdes and and test their hwothesis .. nonexamples. Still others may need explicit presentation of a concept's attrihutes with extended practice in using criteria to classify appropriately. This last strategy depends upon explicit instruction. The previous strategies rewire students toAinferthe concept using examples and noneiamples provided by the teacher. The inferentiallexplicit distinction r--..
should not be viewed as a dichotomy hut as the ends of a continuum which describe actual clas&oom teaching strategies. However, implication of concepts rather than explicit presentation makes concept attainment more difficult: Relating Concept Learning Theory to the Chemistry Currlculum Concept Analysis
According to concept learning theory, the design of concept instruction should begin with a n analysis of the concepts t o he taught ( I , 5.6).This process is intended to clarify exactly what will be taught to students, not to describe the process by which it will he taught. As an example of the type of information about concepts t h a t would be gathered during analysis are the following (hased on the Merrill and Tennyson scheme):
Subordinate Concepts (less fundamental)
Examples: Fats Polyesters Coordinate Concepts:
Carboxylic acid Ketone Aldehyde Amide Amino Acid Anhydride Examples
(1) formal definition of the concept, a concise statement attaching
the concent name to the relevant attributes of the concent. (21 n list ot thecrirical atrr~butes,
(31 a list oithe variable artr~butcs, 1, a list of related concepts imure. less fun~lamenral; conrdinatc).
(
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(5) list of examples (to aid students in generalizing to all members
of the concept set) and nonexamples (to aid in discriminating between members and nonmembers of the set) A possible analysis of the concept ester is included below. For other examples of the analysis of some chemical concepts, see Herron, et al. (7).
Nonexamples
Concept: ESTER .Vote. Tho following analy+iapermits classification oia compound as an ES'I'EH on the ha& of its chemical formula. It is not intended to be an exhaustive analysis, but is, rather, a typical one.
0
II
CHa-C-OH
Definition
An ester is an organic compound that contains the
grouping of atoms (R = H or any alkyl or aryl group; R' or aryl group).
= any alkyl
Critical Attributes (1) The compound must be an organic compound. (2) The compound must contain a carbonyl group, the carbon of
which is singly bonded to a hydrogen atom or alkylor arylgroup (R),and alsosingly bonded to anoxygen atom. (3) The oxygen atom tbat is singly bonded to the carbonyl carbon must also be bonded to an alkvl or awl eroun. (R'): . .. it mav not be bonded to an H, a metal atombr ion,Nkt, or another &bony1 group. Variable Attributes
H'may I,e any alkyl or aryl group, substiruted or unsul,. srirured; H may also be H. (21 The geometrical arrongment, i.a, linear or cyclic. i r variahlr, a* is the representation of the formula in space, e.g., (1) R a n d
(31 A n ester may contain other funct~onalgroupx. r 4 ) A n ester mas contain mow than one ester gnup
In the process of concept analysis, one becomes aware of how comdex manv of the concepts usually presented in introductori chemistry courses act&ly are. her, the choices made to limit the amount of material in a course become more obvious. For example, the list of attributes for the concept ester, as given above, were concerned with the means of recognizing i n ester from its chemical formula. However, one could also teach the concept from the standpoint of chemical s are formed bv rereactivitv. i.e.. esters are c o m ~ o u n d that action of; carboxylic acid a n i an alcohol. An alternative set of critical and variable attributes could be determined. Thus, in courses which taught both formula recognition and reactivitv. students would be exnected to classifv esters on either hasis.'~heconcept learning'task would he d o r e difficult due to the multiple sets of attributes. Choices of concepts to be taught will vary from person to person. Both attempts to gain consensus among staff persons working on concept analyses, and observations of thilecture presentations by different lecturers in chemistry over a seven-year period have convinced me that there is no consensus as to what should constitute the concepts taught at the introductory college level. In fact, it does not seem to matter particularly tbat there is no universal set of material that is nec-~ t o be used in an introductorvcourse. It would onlv seem ~ ~ essary that, whatever choicesof content are made, they should be internally consistent and self-inclusive. Designing - Concept Instruction ~
Supraordinate Concepts (more fundamental)
Examples: Organic Compound Carhonyl Compound Carboxylic Acid Family
Once a concept has been analyzed, instructional strategies to teach it must hedevised ( 8 ) .Concent learnine theow orovides some further suggestions as to how to deGgn ef&&ive instruction: Volume 59
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(1) formal definitionsare a useful mechanism ta present concepts (9); (2) concept attainment is more difficult when critical attributes
are presented over several units of time rather than in a single, , compact unit (2); (3) both examples and nonexamples should be used to teach concepts ( I ) . Additionally, each concept must be related to the teaching of other contents. The order of oresentation of related concepts can h&an effect on the ease with which studrnts acauirr cunrents 110. 11.12). Althourh it would seem intuitivelv logical to piesent more basic c o n c h first, this method does not alwavs lead to easier or more comnlete learning. For example, should the properties of the caibonyl group be taught by showing similarities of reactions of ester, amides, etc., or urould ir b i more effective to directly teach the pruperties of the carbonyl grour),and thrn use these . properties to teach the characteristics ofesters, amides, etc.? Likewise, it is not yet clear under what circumstances coordinate concepts should be presented in serial fashion (one concept presented completely, followed by its coordinate c o n c e ~ tor ) simultaneou& (nresentine each critical attribute for bdth concepts, to allo; for c o m p a k o n and contrast). Snecific instructional decisions will center around the following areas: ~
(1) Use or nonuse of formal definitiom to introduce eonceot
names and attributes. Will the definition he oartial . .~ (contiin only some of the critical attributrsl or cmnpletr contain all uf them,'.' If partial, when and how will the urhrr attrihurrs he introduced? Will concept names be introduced before they are defined? (2) Number and types of attributes that constitute the concept for agiuen teaching situation. If choices are possible, will the concept he taught with one set of attrihutes or multiple sets? How much of the concept will be taught at the introductory level? Do the attributes to be taught constitutea self-consistent and inclusive set? (3) Number and variety of examples and nonexamples to explicate the attributes. Are there examples and nonexamples that illustrate each attribute? Is there a wide range of examples and nonexamples, some of which require obvious distinctions and some of which require fine distinctions? Which of the examples and nonexamples will he used for teaching, and which for testing? (4) The order of presentation of related concepts. Will more or less fundamental concepts be taught first? Will coordinate concepts he taught simultaneouslyor serially? Over what period of time will a concept be taught? Will the attributes be taught incrementally with interruptions to teach related (or nonrelated) concepts? Does the concept become more involved or sophisticated each time it is brought up? (5) The medium or format used topresent the concept. Which parts of the concept will be presented in lecture, discussion, laboratory, demonstrations, films, slides, overhead transparencies, qrohlem sets, etc.? Which parts will he taught explicitly, and whwh parts must be inferred by students? What information, questions, etc., will assist students to make appropriate inferences? Does the amount of material explicitly presented chanee as the course oroeresses? ( 6 ) The ;re and extension orthe conceot. noes the conceot serve '~~~ as a prrrequi-itr concept other cmcrprr, principles, rulrs. or prolhn solving? What tasksorqurstions requir~studrnt~ to combine or extend concepts? How explicit will the links between a concept and other parts of the course he? ~
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Benefits of Concept Learning Theory to Curriculum Planning Anyone who has analyzed concepts with the intent of designing . - instruction from those analvses is aware of the tremendous expenditure of time and effort reauired. T h e auestion becomes: why do it? What can be gainid by attention to concept learning theory? Benefits can he usefully categorized into two classes: better teaching and better learning. 958
Journal of Chemical Education
Improvement of Teaching Concept learning theory has called attention to the factors that influence ease of concept learning. Better teaching comes about when instruction attends to these factors, e.g., presenting both examples and nonexamples of concepts to students. Moreover, better teaching comes about when teachers have more control over what they are teaching. Introductory courses select a subset of the c1;emical universe to present. To students, what is presented is all there is. I t is occasionally difficult for teachers to present topics completely without omitting essential ideas students need for complete understanding. For example, when teaching acid-base chemistry, the concept of a salt is often introduced as a compound that is formed in the neutralization of an acid and base. At some later point, the word salt may be used to represent a type of compound, without being tied to a particular acid-base reaction. In such a situation, students often rightly ask: what is a salt, and how will I know a salt when I see one? How are they to know that salt is a class of compounds that can exist in its own right, with a set of characteristics by which salts may be recognized? Some students can intuit this; many others cannot. Teachers versed in concent learning theow will honefulh become more sensitive to exactly what and how the; have taught. ~ e t t e teaching r also comes about when teachers have more control over how they are asking students to learn. In other words, concept analysis can make teachers aware of how much is being prrsmted explicitly to students and how much students must learn by intuition and implication. For example, a common way to present the concept of Arrhenius acid is to give a partial definition (e.g., an acid is a substance that when dissolved in water gives more Hf than OHions). followed hv two or three examnles of acid formulas - (e.g., HC~,'HNO~, H~SO*).From this presentation, students must decide how to recognize acids from their formulas: what are the critical attributes for recognition (formulas begin with H, etc.) and what are the variable attrihutes (number of H's, etc.). In addition, students must also learn somehow that H z 0 is not an acid, but that CH3COOH is! I am not arguing that increased knowledge of explicit1 i m ~ l i c i tteaching balances should lead to more exnlicit teaching of concepts. Limits of time for lrcturers may pre;.lude this. Even mure imnortanrlv, inferrina concepts is a skill thnt concept analysis and subsemature thinkers need. auent design of instruction leads toclearer perceptions of this Lalance, &d allows teachers to manipulate the balance when necessary. If initially students seem to be incapable of learning concepts implicitly (and there is some evidence that today's students increasingly lack this basic skill (13)).then teachers have the option of either increasing the explicitness of presentation, or designing supplementary materials which gradually lead students to make more and stronger inferences from presented material.
ow ever,
Better Learning? The above presentation suggests that concept learning theory can lead to more controlled teaching. The question now becomes, does it thus lead to more complete and efficient learning? T h e theoretical picture when applied to classroom situations is not clear. Hekon, e l (11. (7) have pointed out that most mncept learning theory was developed through research on concrete. maninulative concents in a lahoratorv settine. It has not yet h r r ~ ;demonstrate; enper~nrenall; that &ch theorv is d~rectlv tu the teach~neof ahstract con.ao~licable .. cept&hich can only he represented by symbols or "pseudoexamples" as is the case for most introductory chemical concepts. More importantly, the link between teaching and learning is not as direct a s one would like. It is extremely difficult to
design an experiment to show unambiguously that better teaching leads to better learning. Conclusion It is not necessary (or possible) for one to analyze all the concepts that one hopes to teach. Initial attempts at analyzing only a few concepts can help to develop the sensitivity to instructional parameters, and eventually to the development of instruction which is appropriate to a particular group of students. If initial use of concept learning theory is satisfying, more extensive amounts of materials could become involved. Concept learning theory is no panacea for all the ills of education. It involves helping students learn to classify appropriately, chemical content. Classification is a relatively lowlevel skill when compared to other tasks such as using rules, applying principles, and problem solving; but it is a fundamental skill. Concept learning theory can be used to call attention to important aspects of teaching and learning concepts, leading to more control and less frustration by teacher and student alike.
Literature Cited
(11 Merrill, M. D, and Tcnnyson, R. D., "Teaching eonceptr: An lnstrvdional De3ign cuar"~ ~young iuniversity, ~ ~ h iof ~~ ~ ~ ~ ih~ e a r ct~h , D ~ ~ ~ ~ and Evaluation. Salt Lake City. UT, 1975. (21 C1srk.D. C., J. Educ. Pryeh.,62,253 (19711. (31 Klausmeier,H. J.,Edue. Psych.,9,1(1971). (41 Klausmeier, H. J., Ghatala, E. S, and Frayer, D. A., "hvels d Concept Attainment and the Related Cognitive Operations: Theoretical Paper No. 40; Research and Develo~mentCenter for Comitive Learnina. Madison, WI,1972. (51 Markle, S. M. sndTiemsnn, P W.,W W ~ ~ ~ l l y ~ ~ d d dCccccptt: d f f f d i ittg in Frumiou8 Pursuit of the Jsbberwock: Stipes Publishing Company, Champaign, IL,1969. 16) Fraver.D. A..Frderiak. W.D, and Klausmeier. H. J.."ASeheme for TestinetheLevel
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