D. SCIENCE ROUND TABLE

THE VALUE AND LIMITATIONS OF QUANTITATIVE WORK IN PHYSICS AND CHEMISTRY

GEORGE C. BUSH, SUPERVISING PRINCIPAL, SOUTH PASADENA, CAL.

Much has been said and written of late concerning the value and limitations of quantitative work in physics and chemistry. One has only to flip over the pages of such school magazines as School Science to see that this kind of work has been the cause of much thought and discussion. Before entering into a consideration of this subject I wish to make a few statements concerning the presence of physics and chemistry in the curricula of high schools. First, they have long ago established their claims as instruments of education. Second, while unusually rich in opportunities for arousing interest and developing power, they should not be expected to yield strange and marvelous results. They should be judged just like every other subject in the course. Physics and chemistry cannot be given with a guarantee to make a student out of a failure in other subjects because of interesting apparatus and amusing phenomena. They sometimes do this thing and perhaps a little oftener than textbook subjects-this on account of the laboratory method which enables the teacher to diagnose and prescribe for the individual rather than the class. Third, the aim of physics and chemistry is to sharpen the observation, teach accuracy, develop reasoning, bring the pupil face to face with the unity and harmony of nature, give useful information with which these subjects are teeming-above all to develop power.

The charge has frequently been made, and by persons high in the educational world, that these subjects are not as attractive to pupils as they used to be, especially physics. Dr. G. Stanley Hall shares this view. They may not be as attractive, but we certainly believe that as they are now taught they are more powerful as instruments of education. I recall my own extreme enthusiasm in physics as a student in the high school fifteen years ago, where nothing bordering on quantitative work was attempted, where we simply reveled in the recitation of the wonders of the science, and where on examination I worked a problem in momentum by multiplying the mass in pounds by the velocity in feet per minute and received a perfect mark, while the superintendent's son, who had a key, solved it by multiplying the mass by the velocity in feet per second and was marked wrong. We were fascinated by the subject except for the mathematics, loaded with erroneous ideas, made imaginative to a degree, deluded into thinking we knew a great deal about physics and anxious to learn more, but, after all, left to learn at some future time the real science and to profit by its course of reasoning. I recall my struggle with my first year's work in university physics. Quantitative work may not give entertainment of the "oh my" type in which the science is lost in the confusion of mind likely to accompany the experiment. Quantitative work well done will, however, give that inward joy, the feeling of power, the pleasure of the philosopher that prompts the student to further and greater activity. This is a thing that counts strongly in education. I do not mean to say that quantitative work has the advantage over qualitative in prompting additional efforts. The reverse is true, ordinarily, but quantitative work in doing this does infinitely more for the student in developing his powers. For purpose of entertainment, for arousing that wild enthusiasm which we hear teachers once were wont to impart to pupils, we will concede that quantitative work has its limitations. More is demanded of us, however, than the creation of a desire to do some real work in the subject somewhere, some day.

The term quantitative work, it seems to me, has taken on an exaggerated meaning, made to embrace work bordering onto research, giving the notion that it is very technical and very difficult, and thereby bringing itself into disfavor as high-school work. Quantitative work does not need to be difficult—in fact it should be made as easy as possible and yet accomplish the purpose. In point of difficulty, intricacy and expense of apparatus, and in time consumed there should be no great difference between qualitative and quantita

tive experiments. There is likely to be a difference in difficulty on account of the teacher's inability to make the pupil get out of the qualitative experiment all that should be gotten. The mathematical nature of quantitative experiments necessitates finer work and the pupil is not slow to recognize this. It is surprising to see how much pleasure is manifested bý pupils in being able to test the accuracy of their work. They soon come to prefer this kind of laboratory experiment. They say they know when they have finished. We all like definiteness in a task.

The chief limitations of quantitative work result I think from the selection of experiments and the presentation by the teacher. The teacher is then, after all, if empowered to select the experiments, the cause of the limitations. I have no patience with the set of arid, parched, and lifeless experiments which start out with work with the sliding scale, vernier and micrometer calipers, spherometers, chemical balances, etc.; not that these things are not of value, but that the proper time to study them is when they are called into use for a definite purpose. The vernier and micrometer calipers are not interesting to the average boy or girl and excite curiosity and respect only when the need is seen of exact measurements, which time may be late in the course, perhaps when the barometer is used and when the laws of strings and the resistance of wires are studied. The question of quantitative work is hopeful if the pupil can be led to the point where he wants to know and wants to do in order to find out more. He should then be given the opportunity to do. James says that it is not in the moment of their forming but in the moment of their producing motor effects that resolves and aspirations communicate a set to the brain.

The quantitative experiments should be selected not for their disciplinary value but for their use in elucidating and verifying the work of the classroom for which purpose they are indispensable. Suppose, for example, we are beginning on a course in chemistry. Oxygen and hydrogen have been studied. The law of definite proportions is then presented. What possible reason can there be for asking the pupil to accept this on faith. Why not let him convince himself of its truth by a few simple quantitative experiments like burning a known amount of magnesium and weighing the product, and decomposing a known amount of potassium chlorate and getting the products? Where is the difficulty in these experiments that should bar them from the course? Why should a pupil be asked to accept the statement that one-fifth the air is oxygen when by means of a bottle, a graduate, and some pyrogallic acid he can soon demonstrate it? With what joy he reports a result which approaches the accepted amount and with what positiveness he states it when later asked to give the composition of air. Is this not worth while? A simple experiment like this, however, requires the closest supervision of the teacher, without which any quantitative experiment is likely to fail. Guidance at every step is imperative.

What would be thought of a course in chemistry that omitted a discussion of the combining weights of the elements and of the atomic theory. Why not introduce the pupil to such a theory by a series of experiments in hydrogen equivalence? They have a right to ask why when these laws and theories are presented to them. There can be no objection in point of time spent, difficulty, or expense, in finding the hydrogen equivalent of zinc, magnesium, and aluminium that is commensurate with the great value of such experiments. And so on thru the entire course. Thru experiments of this kind one gets a realizing sense of the laws of nature by coming into direct contact with them. Confidence in nature is established.

In physics how can the exactness of an exact science be impressed unless quantitative relations be demonstrated? It seems to me that it would be like throwing away ammunition for a teacher to fail to make use of the many quantitative experiments possible in this subject. They above all others, in addition to the light they shed upon the subject, afford to the pupil the means of developing observation, reasoning, and imagination. The personal equation which enters so largely into every quantitative experiment adds attraction to it if reasonably accurate results are within the limits of possibility of the apparatus. In no other way can accurate notions of the various physical units be impressed. A

calorie of heat means something after the specific heat of a few substances has been found. Pupils may give with absolute accuracy the definition of a unit without understanding its real meaning. Why does a pupil go into the laboratory after making a fine recitation concerning the insulating properties of cotton and wrap the cotton covered wire around the binding post and expect a flow of current. I have watched this matter for eight years and have seen it happen again and again. Often the best pupils were guilty of this. Of course the mistake was often soon detected and corrected yet it emphasizes the need of direct contact with the things under discussion to get a realizing sense of them.

In disciplinary value quantitative work excels. Keener observation, more cleanliness. greater accuracy in manipulation, better reasoning, and a finer comprehension of the entire experiment is necessary to success. The co-operative method of getting answers common to all departments of work finds little application in closely supervised quantitative work. The classes, however, should be small and all computations should be made in the laboratory.

I have already said that the real limitation of quantitative work is not the fault of the experiments. The teacher is responsible for its shortcomings. I have taught classes in history, mathematics, and different branches of science and I am ready to say that there is no comparison between directing quantitative laboratory work and teaching other subjects. If quantitative work accomplishes what I claim for it, then a generous amount of good hard work must be done by the teacher. I know from personal experience what will happen if the teacher relinquishes even for a short time his hold upon the work. To begin with, the experiments must be carefully selected to illustrate points that have come up for discussion in the class. The apparatus must be tested to see if sufficiently accurate results can be obtained to illustrate the point. Sources of error must be removed or pointed out and then the most careful vigilance given in order to correct blunders, assist in difficulties, suggest modifications, direct the reasoning, and even to help frame conclusions. I would not burden the pupil with percentages of error. Perhaps you are saying, Why not let the teacher do the experiment? It certainly would be easier for the teacher and insure more accurate results, but what is the course designed for, the science or the pupil? We all recognize the fact that it is easier to do a thing ourselves than to teach others to do it. Even if the teacher does do half the work and the thinking, the pupil is better off than if the teacher had done it all, expecting the pupil to follow it and grasp it. It must be remembered that we are using the subject-matter of physics and chemistry as means of education of the pupil. In the hands of a competent teacher, one willing to work hard and long, who knows all the weaknesses of the experiment by personal performance of it, quantitative work will interest, instruct, and inspire.

It has been said that the idea of the grandeur of science has been weakened by too much quantitative work. One likes to revel, it seems, in the utter impossibilities and improbabilities of matters scientific. Great good has been accomplished if quantitative work convinces that something cannot be gotten for nothing, that a vest pocket chemical fire extinguisher is a delusion, and electric finger rings a fake. Who it is that makes all the wild statements as to what will be accomplished by electricity in a few years, how its application will be extended indefinitely and its price reduced to mere nothing? Surely not one investigating its laws. A quantitative study of Ohm's law and associated laws might take the poetry out of such dreams.

Quantitative experiments are doing a good work and will do more as teachers learn to use them. Too much has been undertaken both in extent and complexity. Too much attention is given every year to devising methods of making quantitative experiments out of everything. Heaven knows we have enough now. I believe in progress but I also believe that the average boy or girl in high school has something else to do in addition to his physics and chemistry.

DISCUSSION

W. A. FISKE, instructor in physical science, high school, Richmond, Ind.-It has always been interesting to me, as no doubt it has to others, to watch the growth and development of scientific work. Pick up a textbook in physics fifty years old and you certainly find a book of great interest. It contains not a trace of the word laboratory, not even a quantitative thought. These things were left for later days.

When we consider physics from a laboratory standpoint we find that three stages or periods have existed: first, the period of no laboratory; second, the period when there was a tendency to all laboratory; and third, a more conservative period, or that of a middle ground, a return to more class and lecture work. When we think of this unsettled condition of affairs there comes to our mind an expression of Goethe. A friend once said to him, "Why do you care so much for Homer when you cannot understand him anyhow?" To which this great German replied:

Neither do I understand the sun, moon, or stars, but as I look upon these mysterious orbs as they pass over me day by day, and as I ponder their wondrous ways, I think at the same time: When shall I ever be of any importance, and when shall I know the real truth of things.

That is the main object we have in so often discussing these questions, to find a little truth to which we may anchor our hopes and build for the future.

The purpose of laboratory work is not that of discovery, or not verifications in itself, but as the writer of the paper has said, to bring the pupil to a realizing sense of things; to cause him to know, to think, and to do things that he may find out more.

Quantitative laboratory work possesses a dignified nature. Such experiments give the student the impression that he is doing something, and not that he is merely engaged in play.

This kind of laboratory work may have a bad application, if the experiment is made the end in itself. All experiments should be worked in connection with the laws and principles which they illustrate and should not be delayed until the end of the subject in hand. The number of experiments should be few, as simple as possible, and easily within the grasp of the pupil.

The value of such experiments to the pupil cannot be overestimated. They teach care, patience, accuracy, cleanliness, skill, and careful and systematic thought.

It has been said by a writer in a recent scientific journal,

If a student is able to handle correctly a spherometer or vernier caliper, if he is able to measure the focal lengths of a lens without dropping it on the floor, or if he can handle any piece of apparatus, successfully, wipe it off, and lay it away as he found it, he has made an acquisition for life.

Finally, this kind of work, as has been suggested by the author of the paper, while being alone in the laboratory must have the constant care and attention of the teacher in order to make it of the greatest value to the pupil

CARL I. INGERSON, instructor in physics, Central High School, St. Louis, Mo.Students seek the line of least resistance and find it in qualitative experiments. We have been kindergartenizing education. College presidents report entering students more poorly prepared than ten years ago. High-school principals report the same with regard to those coming from the grades. We can help to make the students better thinkers by

plenty of strong quantitative work.

J. FRANKLIN WALKER, principal of high school, Anaheim, Cal.-On the contrary, work is much better done in the high schools today than it was ten years ago.

C. M. WESTCOTT, Redlands, Cal.—I believe a certain amount of qualitative experiment should have a place. Any supposed weakness of the schools of today compared with those of ten years ago cannot be due to the introduction of qualitative work, since there is today more and better quantitative work than there was then.

A. B. MARTIN, principal of high school, Marysville, Cal.—We have used the plan of giving one day to recitation on a given subject, then two days to laboratory work on the same subject, followed by two days of recitation on the same subject.

The request was made at this point that the opinion of the section be obtained as to the relative amounts of quantitative and qualitative experiment desirable. A vote was unanimous that in physics quantitative experiment should exceed 50 per cent. and onehalf present thought it should exceed 75 per cent. In the study of chemistry it was voted almost unanimously that quantitative experiment should not exceed 10 to 25 per cent.

Lewis B. AverY, principal of high school, Redlands, Cal.—Qualitative work in science gives a philosophical view-point and is generally cultural in effect. Quantitative work is purely scientific. I am of the opinion that a general view of any science should precede its minute scientific study. In the Redlands High School we give a half-year preliminary cultural course in physics which is as nearly compulsory as may be, and follow this by an elective year with strong quantitative work. This preliminary half-year is conducted without textbook and is in the form of illustrated lectures and experimental answers to pupil's questions. The requirement for entrance to the room each day is the prepared notes on the preceding day's work. After a three-years' trial we are fully convinced of the value of this general course for those pupils who get no more physics and for those who take the quantitative work as well. The latter class know what they are doing and where they are going: they see the trend of the work that they do and its general bearing upon the whole subject.

THE USE OF THE MICROSCOPE IN BIOLOGY CLASSES

I. PURPOSE OF WORK WITH THE MICROSCOPE

WALTER M. KERN, PRESIDENT STATE NORMAL AND INDUSTRIAL SCHOOL, ELLENDALE, N. DAK.

Much is being said and written these days about the "new education." Somebody seems suddenly to have discovered, what most of us are inclined to believe people always knew, that the child is dual by nature; that he possesses receptive and expressive faculties; that they are intimately related, "useless each without the other;" that impression must precede expression, and that the highest type of training is that in which both receptive and expressive faculties are jointly trained. The boy who works at the lathe, who turns from wood a cylindrical form, has fashioned his conception in the concrete. The finished product represents impression transformed into expression, and the mental training acquired in mastering the tool, in manipulating the power, instruments, and material, represents that type of education in some quarters denominated the "new." So with the microscope. These two instruments have at least one point in common; they open up a new world to the experimenter. They are the agents thru which his untried powers seek to try, to investigate, to know; by which the mind, thru the medium of hand and eye, acts and reacts upon the unknown and untried; and the proper use of either may well represent that type of training in which the student's powers of initiative are developed in gaining knowledge at first hand, while their use indicates that we have gone back to Locke and Pestalozzi in our attempt to put in practice our educational ideal.

The microscope in secondary-school courses has played a various and diverse part. We have had three types of science-teachers in secondary schools. The first of these belonged to the "old school." He was the teacher whose receptive faculties had been highly trained. He knew his sums and he knew his texts. He believed all the wonderful things that some compiler had written about nature. He knew the names, the pictures, and the derivation of much of the nomenclature of the flora and fauna described. He knew a few of the forms that greeted him afield. He had unbounded faith in his text. He would believe it rather than the evidences of his own senses. It contained an excellent résumé of what someone sometime, somewhere, thought about the things to which it