INDUCTIVE TEACHING AT THE SECONDARY LEVEL'
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SISTER ERNESTINE MARIE, S.C.H. Monsignor Ryan Memorial High School, Dorchester, Massachusetts T H E pro's and con's of inductive teaching of chemistry at the secondary level have been discussed for several Years and as yet we have unified group taking a stand ou the issue. Individuals here and there favor and use inductive teaching, but really, is inductive teaching worth the Does it brim siznificautlv ~ - effort,? ---.- ~ -. " hieher understanding of chemistry? Does it make better students, or rather, does i t make students instead of rote memorizers? I s i t merely a fad that will move on into oblivion? Or is it something we should encourage aud should use to make our own classes more vital, and to make our students more alert and experienced in scientific thought? What is inductive chemistry teaching? Theses and dissertations have been written on this topic; each author has his own idea. However, one thing we all agree on: inductive teaching is the opposite of deductive teaching. But what then is deductive teaching? Here there is more agreement in coupling the terms deductive and descriptive-deductive chemistry is descriptive chemistry. The dictionary defines the deductive method as a form of reasoning from assumed or established general principles to concrete applications or conclusions. It then states that induction is an act of reasoning from a part to a whole, from particulars to the general, or from individuals to the universal. As the term is used in this paper, deductive teaching is that regular type of high school chemistry course in which theory and description are taught in the classroom in which the student spends one or two hours per week in the laboratory following a manual of directions and seeing for himself the physical phenomena already discussed in class. By inductive chemistry, on the other hand, is meant that type of course in which theory and theory only is propounded in the classroom. I n the laboratory the student discovers for himself the physical and chemical properties of elements and compounds. He has no formal set of directions hut only guide sheets and a good reading background on the topic. As Hetland2 wrote: ~
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1 Presented a t the Nineteenth Summer Conference of the New England Association of Chemistry Teschers, Colby College, Waterville, Maine, August 20, 1957. 2 HETLAND, MELVIN, Th~heSeieneeTeacher, 24,172 (1957).
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The inductive method proceeds from the known and observable, i.e., known and observed in the experience of the studentto the problem, and depends upon broadening this experience to the end that the students themselves discover the solution to the problem.. . Tho deductive method, on the contra^, starts with solution rather than u, problem and is for that Gason a xeak motivating device.
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Moreover, deductive chemistry tends to create an aura of textbook dogmatism. Teachers are all too likely to follow a textbook slavishly from cover to cover, taking even the order of presentation of the author, and teaching only what the author has set down within the pages. Is aut.horitarian science true science? Can any scientist today, a t any level of learning, claim that he has reached the ultimate and that there is no need or room for revision? Many a student coming out of this type of dogmatic high school into college chemistry is bewildered by the coutradictions he meets. If the secondary school teacher had taught him to reason, to question, to weigh the evidence, could such attitudes be so prevalent? In teaching inductively a problem may be raised and suggestions given by the students for possible solutions. Teachers should listen to these explanations without betraying confirmation or rejection. When the questions and all possible answers have been presented, the teacher should direct the students to textbooks for further information, or refer them to their own laboratory benches for real, firsthand proof of the point under discussion. Every classroom should use a standard textbook, one copy for each student. In addition, every laboratory should also maintain a shelf of texts for high school and freshman college level. The average student will consult his own familiar text; in most cases it will sufficiently resolve his problems though the better student will consult several books. The type of hook he uses, along with the degree to which he can correlate and assimilate the information, is a superb evaluative tool with which to measure his scientific advancement,. Knowing where and how to look up the answers to problems, and the ability to use a book well, are true skills and ones which we must wish t o inculcate. I n inductive teaching we start with students where they are in their development and build on the experience that they have had. We make the student face JOURNAL O F CHEMICAL EDUCATION
problems, the answers to which are not known to him, but we provide opportunities for the additional experience necessary to the discovery of the answers. Through questioning and discussion we help them relate their known experiences to the unknown. Again, t o quote from Hetland:$ We use reading materials as another source of information that may help them in their work. We continually encourage the studenta to think, to be active, not passive participants. We share their enthusiasm for the insights they have gained. And finally, we have been reasonably true to the scientific method i.e., at no time have we injected the element of "It's-so-becauseI-say-it's-so-or-the-textbook-says-it's-so.,,
A TYPICAL HIGH SCHOOL INDUCTIVE CHEMISTRY COURSE
The following topics are the basis for class work: Atomic and molecular structure Periodic table and classification Simple equations and the laws involved Stoichiometric problems Solutions, suspensions, emulsions and colloids Acids, bases, salts and ionization Oxidation-reduction Gas lam Fhdiortctivity and nucleonics
With five classes a week in which to cover this theory, could not any teacher do a far more thorough job than if he had to handle preparation, properties and uses of Nz, Hz, 0 2 , NO,, Nt0, HC1, 801, COz, HBr, 1 2 , C12, HNOa, HzSOP, sodium compounds, glass, cement, metals, alloys, and a whole long list more? Start logically with structure and lead from it into periodic classification. If our students really grasp the meaning of the periodic table they will know chemistry. Do teachers, as college graduates in chemistry, feel i t is so very important to memorize the preparations, properties, and uses of streams of elements and compounds, and the details of industrial processes like the Bessemer, the Frasch, and the Solvay? Or has their knowledge of stoichiometrical relationships, periodicity, and ionization stood them in better stead? I s there time in the traditional high school chemistry course really to teach Debye-Huckel theory, Broosted theory, and the balancing of redox reactions by electron transfer? INDUCTIVE LABORATORY WORK MOST VALUABLE
Laboratory work will be a great anticlimax if the student has heard and memorized the material in class. He proceeds to fill in his laboratory notebook with the record of phenomena that he knows should happen rather than what actually did happen. Why his reaction did not "come out right" makes little difference t o him. His answers to the questions are right, because he bas been taught those answers in class. His marks will be in accord with what he writes; hence, he writes what he should write. Does this lay a good foundation for a future scientist? Does this make him well grounded in scientific honesty? How is our inductive laboratory work a contrast to this? I n the first place, we use no manual. Second, we use semimicro technique. Third, students use a general outline report form. Fourth, the students have sets of guide sheets for the more involved experiments so that they will not go too far afield in their testing and waste valuable time. These mide sheets are not a
Ibid., p. 200.
VOLUME 35, NO. 1, JANUARY, 1958
directions. They carry suggestions of materials to be used and were designed merely as guides-to keep the students within bounds. A typical assignment: Next week you are to bring a copper penny to the laboratmy and use it as the basis of ten different exnerimenta. In each reilrtion you dwuld islwfiiy all pro.lu~.t* imd write t h equations ~ for rvt.r).cxprrirncnl: d re*!.
What will the average class of students do with an assignment like this? They will read up on copper by looking in the index of their class text. They will find the metallurgy of copper which they will read with little understanding. They will then begin t o see possible small parts of the chapter that are understandable-even facts they can verify a t their own laboratory tables. They will take notes to the effect that copper will react with air and become oxidized and they will come t o the laboratory with the idea of oxidizing copper with a hot flame to hasten the process; they will have found that copper reacts with various acids to produce salts and they will decide to try every acid they can get. They may find out that CuS may be formed, and that Cn(0H)z is insoluble and that the copper-ammonia complex ion is bright blue. They will certainly discover that copper comes in two valence states, plus one and plus two, and the brighter students will delve until they find ways to make both cupric and cuprons salts. So, on laboratory day, all can a t least perform the oxidation reaction by heating a strip of copper in the burner flame until a black scale appears on it. Many surprises may be in store for some students when they start to react copper with the acids. HC1 yields no evidence of reaction, nor does dilute H2SOI. Why? Dilute HN0a evolves fumes; concentrated HNOa,brown fumes. But remember, we have said all products must be identified. Do the studentslearn to use reference books in a hurry! Handbooks, qualitative analysis books, and every standard text on the reference shelf becomes a source of useful information. The students soon learn which books are useful and how and where to look up material. As the year progresses, knowledge and system progress likewise. We use a general outline report form for the study of elements and compounds asfollows: Occurrence and methods of extraction Preparation Laboratory (description and equations) Commercial (descri~tionand eouations) Properties Physical Density, odor, color, taste, solubility, change of state, specid (allotropic fonns, isotopes, etc.) Chemical Stability, relation to burning, reaet,ions with elements, reactions with compounds, test for (description and equations), special (oxidising agent, acid, etc.) Structure Atomic diagram Molecular diagram Ionic diagram Uses Equations which are important and have not been covered in the foregoing sections.
For example, later in the year we examine the oxides of nitrogen and their chemical properties. Poor students can get combustibility and probably will leave the rest of the outline blank because few reactions are suggested in ordinary texts under these headings. But the
good students, those who have grasped redox to its fullest significance, for them there is excitement! "Is NO* like SO2? It seems to me as if it ought to be. I'm going to try its reaction with permanganate." "Can ferrous-ferric changes be brought about by bubbling NO or NOn into the solution? If I use KCNS to trace the presence of the ferric ions I can tell all right." "Coooer and concentrated HNO.. vield " NO*. -, but the labor* tory preparations mentioned in the texts are different. I'm going to see which is better."
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That is why thismethod of conductingalaboratory has such merits. The slow pupils can go along and get by; and for the good students, the sky is the limit. The safety inherent in semimicro laboratory procedures can increase a teacher's courage in the inductive teaching. Even if quite potent chemicals are mixed together, the amount of material used will cause no damage. The hazard of investigating poisonous gases is also reduced, and the cost factor is most favorable to the semimicro method. For 45 students glassware and chemicals cost less than $50 a year whereas the bill was $500 for a comparable class using the macro technique. Has inductive teaching been used successfully with college preparatory classes? Yes. I s it only for the superior student? No. The answers to these questions we have studied carefully for the past ten years and in every class taught inductively the mean scores on standardized chemistry tests and on the College Entrance Board examinations were higher. Statistical treatment of the scores of the lower IQ group (IQ 80100 on the Calif. Test. of Mental Maturity) revealed
To the Editor: As a commentary on the interesting article by Dr. Hans Schindler on the history of the separatory funnel, I should like t o call attention t o a stopperless separatory funnel designed by K. NAKANISHI[K. Nakanishi, B. K. Bhattacharyya, and L. F. Fieser, J. Am. Chem. Soc., 75, 4415 (1953)l and illustrated in the drawing. The funnel is useful in quantitative work, since it is free from losses entailed in opening a stopper and because in the inverted position it is leak proof. I n the horizontal position the funnel can be shaken fairly vigorously, and it is useful in extractions where a gas is evolved during shaking, H m v m UNIVERSITY
CAMBRIDGE, MASSACHUSETTS
LOUISF. FIESER
that they made a marked improvement under inductive instruction. Inductively taught students themselves have found their college worrk easier in the physical sciences, and have spent less time in preparation of assignments than did their deductively taught fellow students. Many more college chemistry majors have come from the inductively taught classes though all classes were matched for intelligence and socioeconomic background as the study was conducted. According to Morris,' "The secondary school program should be so organized that the educational opportunities offered should match, utilize and challenge the students' abilities," and the inductive course certainly does. Weaver5 thinks the "ideal chemistry course would be an experience of learning by doing," and again inductive chemistry measures up to the standard. BoeckBhas found that inductively taught classes are superior to deductive-descriptive classes "in the crucial problem of attainment of knowledge of and ability to use the methods of science with an accompanying scientific attitude." I n summary, we agree with Curtis:' It seems unquestionable t b t ~ tthe inductive method provides better opportunities for teaching the elements of the scientific method. The inductive method makes the laboratory part of the course a fascinating adventure. The teacher who gives it a fair trial will never discard it. Instead, he will make it s. major supplement in all his science teaching. Chem. Eng. News, 34,3258 (1956). MORRIS,VANCLEVE, WEAVER, ELBERT,The Science Teacher, 19, 287 (1952). ' BOECK,CLARENCE, Sn'. Edue., 37, 81 (1953). ' CURTIS,F. D., The Science Teacher, 17,222 (1950).
To the Editor: I should like t o comment that, while the demonstration of the flammability of vapor as listed in THIS JOURNAL, 34, A375 (1957) works with a short trough, it is much more effective if the trough is 10 to 15 feet (rather than inches) long.
To the Editor: Anyone who deals in words should enjoy John H. Wilson's recent article, "Our constantly changing language" (J. CHEM.EDUC.,34, 447 (1957)). But there are several points that seem worth clarification. The word cybernetics does have a history. Wiener says the following about it in his book, "The Human Use of Human Beings": Incidentally, I found later that the word had already been used by Ampire with reference to politiod science, and had been introduced in another context hy a Polish scientist, both uses dating from the earlier part of the nineteenth century." (Page 15, Anchor edition.)
