ELEMENTARY LABORATORY INSTRUCTION*

adventure in elementary laboratory work I believe to be of some importance in designing a laboI%tory course for others. In elementary instruction, wit...
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ELEMENTARY LABORATORY INSTRUCTION* A

Critical Ana&sis

of Aims, Jfefhods, and Accomplishments W . R. CARMODY

Department of Chemistry,

Reed College, Portland. Oregon

INTRODUCTION

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URING the past few years attacks on the economy of elementary laboratory instruction have become more and more frequent. Much has been written and some experimental evidence has been obtained in favor of the lecture-demonstration method and doubt is being cast on the fruitfulness of individual laboratory work. I was induced to speak on this subject this evening because, although I do not believe that lecture demonstration can take the place of or ful6l the purposes of laboratory instruction, I feel that they are not too often attained in the usual laboratory course itself; and that, unless there is a clarification of the objectives of laboratory instruction and a housecleaning of the experiments and teaching methods employed for attaining them, more and more evidence and sentiment will be obtained in favor of the lecture-demonstration method. It seems to me, therefore, worth while to survey critically the objectives of elementary laboratory instruction and the methods of realizing them and to point out uncertain practices that have attached themselves to the traditional laboratory course, and possibly to suggest methods for better realizing the purposes of individual laboratory work. Although nearly a score of years has passed since such contact as a student was made, a memory of my first adventure in elementary laboratory work I believe to be of some importance in designing a laboI%torycourse for others. In elementary instruction, within the laboratory or without, i t is highly important that the interests and advancement of the student be appreciated and ever kept in mind. Much of the difficulty encountered with correspondingly poor results in elementary laboratory instruction is the result of overlooking this important fact. The methods of laboratory instruction and the experiments in general use today are practically the same as they were fifteen or twenty years ago. Any firmly rooted opinion or reaction fresh in the memory after a lapse of fifteen years ought to be worthy of consideration.

chemistry on the objectives of laboratory instruction. It is quite probable, however, that no general agreement could be reached on the relative importance of each or how it might be attained. With some consideration as to importance, I have classified the ohjectives of elementary laboratory instruction as follows: Tofurnish to students opportunity to: 1. Develop interest in experimental work. 2. Develop training in the logical or "scientific" method of experimentation and thinking. 3. Develop facility with and appreciation of or feelingfor laboratory experimentation. 4. Develop knowledge of and familiarity with substances and phenomena by first-hand study. In the above classification the "development of interest" in laboratory work is placed first not because it is considered to be the final or most important objective, but because i t is considered to be most important to the success of the laboratory course as a whole; so important that, if omitted from consideration in the design of a course, the other objectives might well be sought in vain. Similarly, the "development of knowledge" is placed last, not because we do not appreciate that i t is the real objective of most experimental work, but to illustrate the complete dependence, pedagogically, of its realization upon the attainment of the objectives listed above it. One experienced in laboratory instruction has had demonstrated many times that, unless an interest in and a feeling for a subject is developed, any facts or principles learned have little or no significance to the learner and are usually forgotten overnight. The ordinary student registering for the elementary chemistry course is only mildly interested in the subject. He may be taking i t for one of many reasons, only one of which is that he bas dread9 developed a fascinated interest in laboratory work. One of the major problems of the elementary chemical laboratory course is the development of this interest which, as I have suggested, is all-important to successfullaboratory work ..

The incentives to interest in experimental work may be classified as follows: According to Payne [J. CHEM.EDUC.,9. 933 (1932)J 1. Natural curiosity-the desire to know about some agreement has been reached among teachers of things going on about us. * Contribution to a s~nnposiumon Elementary Laboratory 2. hide of accom~lishment. Instruction conducted by the Oregon Section of the American Chemical Society. October 27.1934. (a) Development of an art (physical training). OBJECTIVES

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(b) Attainment of knowledge (mental training). deal only with well-known chemical reactions, while one (c) Obtaining a worthy result (necessitating principally concerned with the study of new chemical both ~hvsicaland mental training). reactions and ~rincinlesshould not involve a difficult -. technic. Experiments involving complex or uncertain I believe that the most important single item essential to objectives and numerous others more adaptable to lecture the success of a Iaboralory course is the development in demonstration than to individual laboratory work should students of the "pride of accomplishment" attitude towerd not be included. Examples of such experiments are their work. With i t the course has balance and reason. the preparation and properties of halogens or other Without it the students might as well be plowing gases except oxygen; ionization, conductivity, hyfields or digging ditches. This attitude can be started drolysis, electrolysis, hydrogen-ion, or other physical very early in the course by lecture quotations, and by chemical experiments; and detailed qualitative analysis. laboratory discussion and criticism. However, it ~ccordingto the objective desired, experiments &ay will be developed and bear fruit in the laboratory work be classified into three tvoes: (1) to furnish trainine in only if the objectives of the course in general and of each logical methods, (2) to &dop iaboratory technic, and experiment in particular are fully comprehended and (3) to develop knowledge of chemical phenomena. appreciated not only by the instructor but by the Type (1) comprises "in the dark" experiments, probstudent as well. Little satisfaction can he obtained lems, and unknowns. Type (2) includes quantitative from the accomplishment of a task the objective of determinations and experiments requiring difficult which is haphazard or not clearly understood. Methods manipulation. Type (3) includes particularly the of impressing these objectives into the conscionsness of "information" type of experiment. students by careful attention to experiment design will I . Method-training Ex$eriments.-There is interest be considered. value and also educational value in test-tube or other method-training experiments, the results of which are EXPERIMENT SELECTION AND DESIGN unknown to the student before the experiment is nnderEvery laboratory instructor ought to know that the taken. The interest is aroused by a normal curiosity final material results of an experiment-a piece of ap- over what the result is going to be. The educational paratus set up, a compound prepared, an unknown value is derived from the necessity for the stndent to solved, or a quantitative result obtained-lose all make observations and deductions unaided by previous significance, become of no value whatsoever, the knowledge of the particular reaction studied. Howmoment the experiment has been checked. Yet the ever, one should not expect students to develop much title, expressed object, and whole design of numerous interest in or obtain much of value from directed test-tube elementary experiments indicate the laboratory result experiments, half or more of the results of which are to be most important and to have permanent value. already known to him. "1x1, the dark" experiments Educational principles are grossly neglected when the should be as much as possible actually in the dark, or "object" of an experiment, as far as the student can they have very little value from any standpoint. They make out, is to obtain a certain answer or a certain have no "interest value" and have in fact negative laboratory result. A title such as "To Determine the educational value, since the student is tempted to put Atomic Weight of Copper" certainly does not express down his preconceived ideas of the results in place of the true object of the experiment. Can one wonder those observed. Altogether too much stress tin be put on this type that the answer alone becomes the important objective C of experiment. One or two placed near the beginning in the mind of the student? On the other hand, a stated object such as "To Study of the course are both necessary and sufficient to inthe Principles of Atomic Weight Determination and culcate habits of scientific experimentation, but such to Develop Technic in Accurate Quantitative Experi- work may very well and often does become a mere catamentation" serves to impress on the student the true loging of results and equations, which, once put in the objective and what he might expect to obtain of per- laboratory notebook, lose significance for the student. manent value from the performance of the experiment. Only the trained experimenter can continue to work It indicates to the student that the most important "in the dark" for very long without losing interest in his part of elementary experimentation is the development experiments, and he has plenty of incentive supplied by of method (the method of thinking and the method of the general aspects of his problem and a more or less doing) and the ideas acquired; in a word, that the definite objective. "Problems" and "unknowns" may be classed also as change occurring within the mind and body of the "method-training" experiments, and the same general student, not within the test-tube, is important. The careful selection of material or experiments for principles apply. They offer the student the opporthe experimental work is important to the success of a tunity to plan and develop his own experiment and laboratory course. I believe that an experiment should carry it out to completion. If they are to have either be selected and designed to accomplish one objective interest or educational value they must be problems only. When too much is attempted, confusion may and unknowns in fact, which the student is to solve result with little accomplished. For example, an ex- unaided by many suggestions from laboratory manual periment involving new and difficult technic should or instructor. Directions should be a t a minimum, A

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only enough to suggest the general aspects of the laboratory problem. Nothing is more deadening to interest than the fully detailed experimental outline with spaces to be filled in by the student with "results." If forced to choose between the two extremesall directions or no directions-I would seriously consider turning the student loose sans laboratory manual, but with a competent instructor, into a laboratory well supplied with chemicals and apparatus. 2. Technic-training Experiments.-Technic-training experiments include simple lass-working, set tin^ up of apparatus, use of inst&me&s and apparatus (such as the balance), and development of quantitative technic. As previously indicated, such experiments may well be placed near the beginning of the course, and, although they may be used to illustrate simple reactions, they should involve no complicated principles or reactions which might be confusing to the beginning student. It is essential for the success of this type of experiment especially that the objectives be fully appreciated by the student and that pride be developed in the attainment of a precision technic. A great part of such experimental work being done a t the present time in elementary laboratories I believe to be an absolute waste of time. A student might make a thousand bends and set up a thousand pieces of apparatus with no permanent acquisition of value unless pains be taken to improve technic, and pride be taken in the result. Pride in accomplishment is essential, and it can be inspired in a hundred ways, by the atmosphere of the laboratory, by the attitude of the instructor, and by the design of the experiment. 3. The "Information" [email protected] considering type 3, tbe "information" experiment, one should not forget that an isolated chemical fact is usually not interesting in itself. Its interest depends upon its significance to or relationship with some other fact or group of facts or its use as an example of some principle or generalization. Likewise, we find it difficult to remember an isolated fact or a series of unrelated facts. We remember data only when we cpn correlate them with one another or with some general scheme in which they are significant. These principles have been demonstrated to the speaker by tests given t o ascertain the information retained by entering second-year chemistry students. Year after year these students have retained very little or no information acquired from an experiment performed in the previous year in which, following the detailed directions of the laboratory manual, they mixed a solution of " A with a solution of "B" and obtained result "C" and wrote equation "D." A student logically may answer an inquiring teacher, "No, I don't remember the result of mixing solution A with solution B. Why should I?" As an unrelated, isolated fact, it would probably not be worth remembering. On the other hand, when questioned concerning an experiment which involved a group of reactions which were generalized, compared, and contrasted after thor-

ough study in the elementary laboratory, second-year students have demonstrated not only an understanding of the principles studied but also knowledge of the detailed reactions involved in the study. As has been recently pointed out by Bateman in the October, 1934 number of the JOURNAL OF CHEMICAL. EDUCATION, designers of elementary courses, as a group, have shown almost complete disregard for these points. Information (test-tube) experiments, each of which may have no relationship with the experiment preceding or the one following, have been designed to occupy one laboratory period. They have filled laboratory periods with so much experimental work, each experiment being regimented to a certain period, that no time is left for a consideration of the significance of the work or a discussion of it with the instructor. I can find no objective in that kind of laboratory work (one cannot call it "instrnction"). I t certainly furnishes no training in logical or independent experimentation and offers very little if any opportunity for the permanent acquisition of significant information. In an effort to accomplish the real objective of the permanent acquisition of significant information, I submit what may be called the "information-study" type of experiment, designed to occupy the attention of the student, working a t his own pace, for five or six laboratory periods. As with the "problem" experiment, few directions are given, only enough to suggest the possibilities of the experimental study. It has been suggested that the laboratory work, especially toward the end of the study, might be slipped over carelessly or neglected altogether. The danger of such practice is slight, I believe, when this type of experiment is given in the second hali'of the course and after the objectives are 6rmly implanted into the consciousness of the student. When "6rst-hand correlated knowledge" is recognized to be the objective of this "study" experiment, satisfaction will be obtained, and interest lags only after all the suggested points are . carefully studied in the laboratory. INPORMATION-STUDY EXPERIMENT LABORATORY AND LIBRARY STUDY OP TEE GENERAL CABHISTRY AND REACTIONS OF THE C O W O N ACIDS

Laboratory work is to be completed without reference to text, notes, or library. PrincipaJ acids of the laboratory and of industry are hydrochloric, nitric (dilute and concentrated), and sulfuric (dilute and concentrated). ImDortant reactions of these acids involve the following classes of ibstauces: 1. Elements (metals and non-metals) Examples: Cu, Pb, Al, Fe. Zn, C, S, Ag 2. Oddes, hydroxides, and peroxides Examples: PbO, PbO*, CuO, Fe*Ol. ZnO, MUG 3. Salts (soluble and insoluble) Examples: NaU. NaAc, BaS08, BaSO,. KI GENERAL DIRECTIONS

(1) Use small quantities. If no reaction takes place in the cold. heat carefully. Recover products in pure farm wherever practical. Record all observations and results to correspond t o each treatment.

(2) Submit for criticism of the instructor. (3) Interpret each result, write in equations you have previously encountered, and submit for criticism. (4) Consult references for remaining equations, include references (for each equation), and submit for final criticism. EXPERIMENT

1. Study the chemistry of hydrochloric acid. 2. Study the chemistry of sulfuric acid (dilute and conc.) 3. Study the chemistry of nitric add (dilute and tone.)

Be prepared to report orally on the following:

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(a) Acids and oxides--general reactionsspecific reactions. ( b ) Acids and metals-general reactions-specific reactions. (c) Acids and saltsprinciples involved. ( d ) Summary of oxidation-reduction properties of the acids studied. SUPPLEMENTARY STUDY SUGGESTION

Suggested topic for paper: Acids in industry. EXPERIMENT ORDER

It is reasonable that in laboratory as in lecture, no student should encounter complex chemical reactions until he has been well introduced into the principles of experimentation and has developed some facility for the subject. The speaker holds no brief for the laboratory manual that starts out with an experiment involving chemical reactions, sometimes with gaseous or other products, the identities of which are to be "proved" by the student who may have had no experience in identifying either reactions or substances. Experiments designed to develop correct methods of observation and of experimentation and experiments to develop facility in setting up apparatus should be placed early in the course. These, along with quantitative technic experiments, all of which require considerable time and a certain-amount of instruction and supervision but which involve no complex chemical reactions, may well comprise tbe whole of the first half. The student so trained can be expected to devote most of his attention during the second half year to the study of chemical reactions, unconsciously using methods and training acquired during the 6rst half. Finally, during the last few weeks of the course, when the most important chemistry has been studied in lecture and in laboratory, laboratory problems necessitating the use of knowledge and technic may be included, in order to offer the student opportunity to apply what he has assimilated during the course. These problems may include "unknowns" requiring simple qualitative tests, semi-quantitative preparations of inorganic compounds, or "what can be done" with selected raw materials. They may be regarded as part of the regular work or may be set up as laboratory examinations on definitely assigned laboratory periods. We a t Reed College have found that an unusual degree of interest is stimulated when these are issued on definite days and regarded as "laboratory examinations."

ELEMENTARY QUALITATIVE ANALYSIS

The extent to which qualitative analysis should be incorporated in the elementary chemistry laboratory course is a subject upon which there are differences of opinion and about which much has been said. The subject is of such importance as to demand considerable attention in a survey of elementary laboratory methods. The qualitative analysis work has been and should he placed a t the end of the year after the important reactions and principles have been studied. I am thoroughly convinced that it should include only simple tests and simple "unknowns" involving chemistry well known to the student. Separations requiring detailed directions and involving principles only partly understood and reactions encountered only once or twice previously are of doubtful value from the interest as well as from the objective standpoint. I t is a recognized principle of scientific investigation that one factor alone should be varied a t a time, yet in first-year detailed qualitative analysis. the student encounters in the same experiment and a t exactly the same time two variable or uncertain factors; viz., the analytical procedures and the chemical reactions and principles involved in the procedures. It may be argued that the reactions and principles, or a t least most of them, have been covered in class work; that the student has seen them demonstrated by lectures and possibly discussed them in class for the 6rst two-thirds of the year, and, therefore, should be able to apply them in detailed qualitative analysis during the last third of the year. My answer, based on experience, is that. h2is not able to do so. After five months' contact with chemistry in lecture, laboratory, and class, the good student knows a good many chemical reactions and chemical properties and a few principles and generalizations. He does not have and cannot be expected to,have the deep appreciation and thorough understanding of the principles of chemical reaction and of chemical equilibrium necessary for intelligent performance of the procedures of detailed qualitative analysis. In evaluating laboratory work, one must keep in mind the objectives and incentives involved. The incentive in qualitative analysis is the satisfaction and the pride in intelligently applying understood reactions and principles to a given problem and carrying it through to a successful conclusion. When the qualitative work is started too early or if it is too complex for the advancement of the student, most of the incentive has been eliminated. Too often the students are unsure of their answer or fail altogether on the "unknown." On the whole, the work is uncertain and the principles are clouded by details of procedure. This state of affairs is certainly not a good example of the "scientific method" of teaching or of learning. Many students do iind interest and some enjoyment in such experiments on account of the "unknown" interest attached (the "knowns" are usually done with

speed and alacrity); but the desire to complete the procedures and report the unknown, together with the short time available, usually causes hurrying through of procedures with little attention being given to the reactions and principles involved, and satisfaction is obtained only if the unknown is reported correctly. On the other hand, to the well-prepared second-year student, detailed analytical experiments are a joy. In the second-year course, time is available for the demonstration of every chemical reaction and a discussion of every principle in class and an investigation of each reaction and each process carefully by means of "study knowns" in thelaboratory before the"unknown" is undertaken. It has been my observation that the general success in a course of qualitative analysis is directly proportional to the time spent on preparation. Extrapolation of this relationship back to the meager preparation of the freshman student after five or six months' study might well indicate the fruitlessness of detailed qualitative analysis in the elementary course. There is a tendency both in high-school and in firstyear college chemistry to incorporate the material of analytical chemistry and of physical chemistry, the true appreciation of which requires years of chemical environment. This tendency is abetting the most common fault of elementary laboratory courses, a fault that lies a t the root of most of the uncertain methods and practices now in use: too much is athmpted in too short a time with too few trained, interested instructors. The result often is what might he expected: all too little of anything worth while is accomplished. GRADUATE STUDENT ASSISTANTS

The college or university that uses graduate students to make up the entire corps of instructors in the elementary laboratory evidently does not greatly value its laboratory course. The recent graduate, whose major interest is tied up by his graduate study and research, usually has little interest-and cannot be expected to have much in the objectives of the elementary laboratory course he is supervising "to dkke expenses." Nor can we expect efficient instruction even from one who is interested in teaching if he is turned loose in the laboratory to supervise, yes and to inspire, the work of fifteen or twenty students without previous experience and without the benefit of daily guidance and criticism of an experienced teacher. Such neglect may account for the stereotyped "direction-result'' type of experiment so prevalent in our modem laboratory manuals. These experiments require only a casual inspection by the instructor with corrections and grade. This can be done by the uninterested, inexperienced graduate student who may spend most of the laboratory period at work on his own interests. There may be economic excuse for the use of inexperienced graduate assistants in the larger universities where the per capita expense is low (although it is questionable logic that the per capita expense of a large laboratory class demanding many instructors must be kept low by hiring incompetent, inexperienced assist-

ants, while experienced men are required for the smaller laboratory classes of the second, third, and fourth years), but there is no excuse for the practice of "turning them loose" without constant supervision and advice from experienced teachers interested in elementary laboratory instruction. Unfortunately, or perhaps fortunately, my teaching experience has been limited to classes demanding one or two laboratory instructors only; so I can speak with little authority upon the solution of problems involved in providing laboratory instruction for five hundred students or more. I believe, however, that much can be done to improve the quality of "graduate assistant instruction." The problem is to obtain interested, understanding instruction; interested because the student's interest is usually no greater than that of his instructor; u d e r standing, because, as I have said earlier, there is little likelihood of the accomplishment of an objective unless it first be understood by the instructor. To solve the problem, I suggest that every graduate instructor be required to take (for credit) a course i n elementary laboratory instruction, to be given by the professor in charge of the elemenlary laboratory and to comprise discussions of the objectives and methods of instruction for the course in general and for each experiment before it is approached in the laboratory. Merit received a t the end of the year could be based upon how well the graduate student has applied to his instructional work the principles and methods discussed in class. Such a course, by calling attention to the technic and dignity of competent laboratory instruction, should serve to stimulate interest as well as furnish understanding. .. SIDE-SHELF REAGENTS

Every effort should be made to eliminate any method or practice that tends to interrupt the even, continuous. serious work of the laboratory. Long waiting a t the stockroom window for service should not be countenanced. I have heardargumentsagainstside-shelfst& of materials and solutions and have seen them discontinued principally because they have encouraged waste and slovenliness on the part of students who roughly "dump out" two or three times as much as needed because it is free or chargeable to the class as a whole. I believe, however, that these abuses are wholly unnecessary and that they can be eliminated by careful attention to the following details: 1. Instructions on use of side-shelf reagents a t the first meeting of the class. Instructions also are given on pouring solids and liquids from bottles, the use of small and approximately exact amounts. 2. The use of small containers. A small bottleful of material or solution is said to last as long as a large bottleful. At least the use of small bottles suggests the use of small amounts. 3. Perfect order and arrangement of side-shelf. Roll of paper and scales provided for approximate weighing of amount taken.

4. Frequent inspection of side-shelf, especially for the first mouth. Those who fail to do their part will soon be found out and a suspension of the privilege of usingthe side-shelf for one or more periods may be meted out to the offendingparties. Young people are usually willing to meet the instructor half way. If he does his part and also lets them know what is expected of them, they will generally do theirs. I have seen side-shelves perpetually in a state of disorder and slovenliness and also those always in perfect order and cleanliness. The difference, I believe, cannot be accounted for by differences in students but by differencesin instruction. A slovenly side-shelf usually indicates that the admimistration or instructor or both have failed to do their parts. CONCLUSION

I n conclusion, I wish to repeat that, in general, elementary laboratory instruction has received a bad

name not from its serious use but from its misuse and ueglect. The results of abuses such as the gross ueglect of objectives in course design, the attempt to accomplish too much, the employment of inexperienced, uninterested instructors, and regimentation of students through experiments are being justly questioned. We usually get no more than we pay the price for, and laboratory instruction is no exception to the rule. Elementary laboratory teaching is an important as well as a highly interesting work and worthy of the time and effort of the best ability of the chemistry department. When this is realized by the chemistry faculty, as well as by those in charge of the college budget, the elementary laboratory may receive the quality of instruction that its importance demands. Some have considered it important enough to defend, but have we considered it important enough to do auything about--do anything about producing results which may justify its defence?