EVALUATION OF ACHIEVEMENT I N CHEMISTRY' MAX D. ENGELHART Chicago Public Schools, Chicago, Illinois
1.r 18 generally accepted that effective instmetion in chemistry involves more than the imparting of the content of a text. While acquisition of knowledge of facts and principles is a major objective of chemistry instruction, other important objectives should not be neglerted. These include the ability to apply facts and principles to problems requiring abstract or critical thinking and the attainment of desirable attitudes, ideals, and interests. Laboratory instruction, in addition to developing numerous manipulative skills, should also contribute to the acquisition of all of the objectives referred to above. Where teaching is restricted to the imparting of knowledge and no serious effort is made toward t,he attainment of a broader range of objectives, there is little justification for use of tests containing other than factual essay or objective exercises. It is the purpose of the author to offer suggestions which should prove useful to teachers of chemistry interested in t,he evaluation of a comprehensive range of ohjertives. Kno\rledge of facts and principles can be evaluated hy means of either essay or objective exercises. I t is more efficient, however, to measure the acquisition and retention of knowledge by means of the latter. Since many more objective exercises than essay ones can he answered in a given time, it is possible to secure much more representative samplmg of knowledge by using objective exercises. Furthermore, because of the greater number of exercises and the objectivity of scoring, the reliability of the measnrement is usually higher. When essay questions are used they should be confined to thought questions. They should not be too specific and detailed in character. An essay quest,ion which asks the chemistry student to describe the operation of a blast furnace a d h respect to: (a) the charge of limestone, coke, iron ore, and hot air; (b) the combustion of carbon to carbon dioxide, the reduction of carhon dioxide to carbon monoxide, and the reduction of iron oxide by carbon monoxide to iron; and (c) the funct,ion of limestone as a flux or slagging agent, gives the student littalefreedom with respect to what to say and how to say it. A mere request to describe the operation of a blast furnace should stimulate not only recall of facts, but also discriminative thinking in the selection of farts and greater effort and originalit,y in organizing them. It is often effective to nse essay questions which ask the student to compare or cont,rast. For example, 1 Rnsrd an a paper presented at the 118th Meeting of the Arn~riritnChrmirnl Societ.y. Chicago. Srptemhrr, 1850.
,'Compare respiration in the living cells of plants a n d animals with ordinary combustion" and "Contrast, the formation of compounds by electron sharing wit)h the formation of compounds by eletTron transfer." Such questions are most likely to stimulate thinking on the part of the student, if instruction, though covering the things contrasted or compared, has not involved point by point comparisons, or contrasts. Sometimes it is possible to formulate essay questions which involve applications of general principles to situations or problems novel to the student. For example, suppose that a class has been taught the prinriple of the activity series of met,als and that thr more usual applications have been given. Then, at some later time, an essay test may inclnde the question : "A photographic print contains line grains of silver. Explain why immersion of such a print in gold chloridr solution will result in a different appearance or tone." Other possibilities for good essay questions of thin t,ype can be based on descriptions of experimental data. novel to the student, but having relations analogous to data with which he has had experience. Sometimes the data thus presented can be accompanied by inferences drawn from them which t.he student is asked t,, evaluate or to criticize. In addition to essay questions of the kinds referred to above it would seem appropriate to frame some which have to do with the place of chemistry in contemporarjlife. Such questions may be of great. value in integrating the teaching of chemistry with instruction in other fields. For example, "Compare the possible consequences of the introduction of atomic energy in industry with the consequences which resulted from the int,ro(hotion of coal as a source of power" or "Disauss the cont,rihution of the science of chemistry to the health of the community." Quest,ions asking for the int,erpretat,ion of data novel to the student, or which are of the type referred to in this paragraph, not only provide the inst,mctor with bases for judgments with respect to the thought patterns of the students, they also provide the instructor with opportunities to evaluate the acquisition of attitudes, ideals, and interests. Careful analysis of the responses of the students should provide answers to such questions as the following: To what extent is the student able to recall, select, and evaluate relevant facts? To what extent is the student able to organize his facts and to apply them to the ~ituationrepresented by the question? To what extent is the response of the student colored by biases or prejudices? To what ext,ent does the student exhibit
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critical judgment with respect to the facts he mentions? Does the student tend to go beyond the facts, or is he overcautious in generalizing? What attitudes or values is the student acquiring? The responses of the student,^ may he rated with respect to such characteristics and the ratings combined to yield scores on the essay test as a whole. More important, however, than using such test,ing as one means of determining course marks is to use it as a means of evaluating the attainment of important course objectives and as a. basis for the better direction of the instruction to the individual students immediately concerned.' Before turning our attention to the writing of objective exercises some reference should he made of the contiibution essay examining can make to t,he proper eduration of science and engineering majors. Responsibility for giving such students training in the writing of reports of research cannot wholly be left to English teachers. Such students need experiences in the locating of published information concerning scient,ific problems. They need practice in evaluating the relevance of such information. They need to acquire something of Darwin's attitude toward dat,a which disagree with a hypothesis tentatively held to be true. They need to acquire ideals with respect to the importance of accuracy in taking notes and in citation of sources. Finally, they need t o acquire facility in organizing and summarizing what they have read. The providing of such experiences may be a means of enriching the rurriculum for the superior student, of securing greater motivation through the challenge to his abilities, and of increasing his interests in the field of chemistry. Facts, concepts, or understandings essential to effective thinking in chemistry should form the basis for numerous objective exercises. Before nrriting an exercise relevant to some fact, consideration should be given to the importance of the fact. Is it a fact that the student needs to know if he is to comprehend later instruction? Is i t a fact necessary to the solution of some important problem? Does it enhance understanding of some basic principle? After such facts or concept,s have been identified, one or more types of objective exercises may be written. Each series of exercises, however, should consist of items of the same type to avoid confusion with respect to directions. If you feel that you must write true-false exercises, avoid writing bmad generalizations which are all too obviously true or false. Avoid also the writing of long, involved statements containing qualifying phrases. Test,-wise students realize that such statements are usuallv true. Furthermore, the truth or falsity of a true-false exercise should not depend on the meaning of some obscure word or minor detail. One means of 9 For a more extended diseu~sionof these points of view with rexpect to essay testing see: VBRNER M. SIMS, "The e 8 S W examination in a projective technique," Eduentionnl nnrl Pwcholoy
