VOL. 6, No. 9
METHOD OR CHEMICAL INSTRU~ION
1525
A METHOD OF CHEMICAL INSTRUCTION J. A.
S O ~ R BOMBN N , HIGHSCHOOL, SALISBURY,NORTHCAROLINA
In connection with our classes in chemistry this year a plan has been carried out which has been both interesting and instructive in its results. The first idea of the plan came to the instructor last fall when one of the students asked, "Why can't we see everything we study about?" The project consisted of preparing: displays of chemical compounds with their preparation, properties and uses, with special emphasis on their uses; charts of the common elements with their valences; and charts of radicals with their valences. The objects in carrying out the project were: (1) to help the student to better understand chemical processes and reactions, (2) to develop the interest of students taking chemistry in the subject so that they may desire to pursue it further in higher institutions, (3) to arousc an interest in the students of lower grades in the subject so that they may have a desire to study chemistry when it is offered them, and (4) to develop a spirit of appreciation, in the students, of the relation of chemistry to their every-day life, of the contribution of chemistry to the scientific age in which we live, and of the opportunities that living in this scientific age involves. Special emphasis has been placed on the uses of chemicals on account of the last purpose. All the work has been done by the students after school, under the supervision of the instructor. A small storeroom in the laboratory was used as a workshop. At the outset the big problem was the collection of materials. Of course most of the chemicals could be secured from the storeroom, but chemicals and reagents alone did not furnish the desired amount of material so the students wrote letters to manufacturing concerns asking for samples of raw materials and finished products. Much material was obtained in this way. The preparation, properties, and uses of the materials mounted were obtained by the pupils from reference books in the library. The students took much interest in looking for these facts, an interest which otherwise they might not have had; this gave the pupils knowledge which they would not have secured otherwise. There was quite a bit of competition between the students as a prize was offered for the best project. This had a tendency to make the displays neat and attractive as well as instructive. The projects have been much used during the regular recitation period. For instance, one boy made a display of salt and its products. Starting with the common salt he showed the important products which are derived directly and indirectly from this compound. When sodium and its compounds were studied during class periods this particular display was used very effectively. The preparation of sodium by the electrolysis of fused
sodium chloride and reactions between various compounds and sodium producing sodium corrpounds were better understood by use of this display. Many other displays of a similar nature to the one mentioned above have been and are being used. For instance, a project of potassium compounds was devised in which one student made several of these compounds out of wood ashes. By leaching the ashes the potassium salts were taken out and from the resulting liquid several compounds were actually made and purified. This particular project was very interesting from the instructor's as well as the students' point of view. The rubber exhibit was quite attractive and instructive. A local tire company furnished most of the materials for this exhibit. Starting with the smoked para and displaying the other materials and ingredients, stages in the manufacture of automobile tires were shown. Different grades of cord, with and without the rubber, used for different parts of the tire, results of vulcanization, and tread work were some other phases projected. Though the actual reactions which take place when rubber is chemically treated are not known, this exhibit has been very fascinating for the chemistry classes, as well as for others, who have seen it. A glass exhibit has also been used quite effectively. All the materials for glass making, both the necessary ingredients and other substances used for the production of special grades, types, and colors of glass were employed in the project. Along with these materials the varieties of glass which they produce were used. For instance, amall amounts of silicon dioxide, sodium carbonate, and lead oxide, together with the type of glass these produce, were shown. Different materials which are necessary to produce different colors, with the special color of glass produced, such as some cobalt compound used for blue glass, manganese compounds for pink or violet, depending on the amount used, and selenium compounds for a clear red glass, were shown. The exhibit of carbon and some carbon products was, too, very interesting as well as beneficial. The allotropic forms of carbon (lampblack, graphite, and diamond) were shown together with their principal uses. Of course a substitution has t o be made for the diamond. Some of the commercial uses of these were illustrated, not only by materials, but with literature concerning them. The materials necessary for the manufacture of carbomdum were shown, with samples of carborundum and its uses as an abrasive. One boy made a chart of valences and radicals. A large piece of white board used for sign painting served as a mount. He selected about thirty of the most common elements and about the same number of the most common radicals and arranged these in alphabetical order. The symbols for the elements with their valence and valences were printed on one section of the chart while the name, formula, and valence of the radicals were
VOL.6, NO.9
METHODOP Cx13rnc.4~INSTRUCT~ON
1527
printed on the other part of the hoard. Letters and figures were one and one-quarter inches high. The electrical charges carried by each radical were indicated with plus and minus signs after each formula, the number of marks indicating the valence. This chart has been used very much by the students as a help in writing formulas. The instructor has, several times during class, employed the chart as a means of instruction. The students were divided into two groups, a captain being appointed for each side. These chose their sides, and a formula "bee" was conducted. The names of compounds were called out by the instructor, first to one side and then to the other. The contestants would give the formula, and when one missed the person missing it would take his seat. As soon as half of the members of either team were down, one of them had the privilege of answering for one of his colleagues who had just missed and, if correct, would change places with the one who had missed. This helped to keep the interest and attention of the students after they had been put down. Likewise the formula was given and the student would give the name. After some drill in this fashion the chart was covered up and the contest continued without it. This has been an exceedingly good method by which to teach formulas, names of compounds, radicals, and valences, knowledge which ordinarily has very little interest for the students, and knowledge which is sometimes neglected. There were many other projects both in form of displays and charts which have been used and are being used to a very good advantage in the chemistry classes. Space, however, is not afforded for discussion of all of them. However, it is hoped that some materia? in this article may be of value to other chemistry instructors, even though this as presented has been very incomplete.
