David L. Powell, R. H. Bromund, L. W. Havnes.. K. D. McElvanv. and J. D. ~eders& College of Wooster Wooster. Ohio 44691
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In cooperation with the Wooster Art Center, a non-profit community organization, we recently had the opportunity of teaching a nine session summer course in chemistry for children aged 9 through 12. At these ages children in the public schools have had very limited exposure to science except for a little descriptive biology or botany. Any acquaintance with chemistry usually must wait until the students reach high school. The students in this course were entranced with the idea of chemistry and can only be described as overjoyed a t the chance of taking such a course. At the conclusion of the session we were satisfied that the students had begun to learn how a scientist operates sevwal years sooner than they would have otherwise. We feel it is worthwhile to share our ideas and experiences. The emphasis throughout the course was on the students actually performing experiments and recording the results. A few demonstrations were done, but for the most part the students were in the laboratory. We resisted strenuously the frequent temptation to lecture ahout what they were doing and were gratified a t how well the students understood what they were doing. The key to good understanding was a very low pupil to instructor ratio. The class met three times a week for ahout one hour and 20 minutes per session. Originally one-hour sessions were planned hut the time was lengthened because the students were enjoying the class and because they worked more slowly than we had anticipated. Each student was provided with very simple 'equipment (a beaker, four test tubes, a test-tube rack, a Bunsen burner, a squeeze bottle of distilled water, a towel, litmus paper, and safety glasses) which could he left on the bench top between classes inasmuch as regular college classes were not in session. Each student also had two bluebooks in which to record ohservations. One of these was kept in the laboratory; the other was taken home when observations were to be made there. We felt that this record keeping was at the heart of our course. We found early that nine year olds write very slowly and painfully; hence, their records were almost always terse hut usually still decipherahle. The students were much hetter a t immediate recording than are college-age students. They were also more fearless than older students in recording what they saw (or thought they saw) rather than trying to figure out what we thought they should have seen. Our only real struggle with their recording lay in their confusion of ohservation and conclusion. When not challenged, they often omitted recording an observation but instead directly recorded a conclusion. In deciding on course content, we thought that it should, where possible, impinge upon their previous experience. Thus we mentioned, used, or investigated common household materials when we could. On the first day of class, each student was given a mimeographed list of 26 of the most common elements and their symbols and of seven common ions and their symbols. It was suggested that these he learned within the first week. The elements and their symbols were learned; some of the ions remained a mystery. The students were told the color changes which litmus paper undergoes and were then sent to the laboratory to classify nine different suhstances, e.g., ammonia, boric acid, sodium chloride, as acidic, basic, or neutral. They were also provided with solutions of three in-
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Kiddie Chem ,4
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dicators and asked to find their acidic and basic colors. At the end of the first class, each student was eiven six nieces of litmus paper with which to classify as many subsiances a t home as possible. On the second class day, the students tested the action of HCI and NaOH (both 1M ) on a variety of substances, e.g., a penny, an iron nail, NHdC1, MgO, PhS, CaC03, noting whether the substance dissolved, changed color, or whether any gas was evolved. The students were also told to bring in expendable items from their homes for testing with acids and bases. T o avoid dangerous combinations, each item or material was cleared with an instructor. On the third day, a conductivity apparatus on which light hulhs of various wattages lighted when the circuit was completed was used in a demonstration. Ions in solution were mentioned as being the means of carrying current through a solution. Various solutions of salts, strong and weak acids and bases, a non-electrolyte, tap and distilled water were classified according to which hulhs could he lighted. In the laboratory, the acidic or hasic nature of the gas produced by the action of 1 M NaOH on ammonium ion and of 1M HCI on carbonate, sulfide, acetate, and sulfate ions was determined using damp litmus. Sulfate was included to see how good their imaginations were; they roved less suneestible than we exnected. At the beginning of the next class, we demonstrated the action of water on six different metals: sodium.. . ~utassium. calcium, magnesium, iron, and nickel, and of hydrochloric acid on those of the six which did not react visibly with water. The solutions formed by the dissolution of the metals in water were tested with litmus. The physical appearances of the metals were noted (sodium, potassium, and calcium after being freshly cut) and the metals were all found to he good conductors. The procedure for carrying out flame tests was also demonstrated. The students then carried out flame tests on solutions of various metal ion nitrates, Na+, K+, Ca2+, Mg2+, Ba2+, Fe"+, Ni2+, and checked the reaction of the metal ions with various anions, e.g., C0a2-, S2-, Sod2-, and with aqueous ammonia. This latter s t e was ~ so interestine land so time-consumine) that it occupied the bulk of the next class. The students f*d the most difficulty with, and were most intrigued by, the concept of a precipitate. For example, the reactions between barium and sulfate ions was invariably said to give a milky solution. Once the students had been shown the tiny flecks of solid which had formed,. thev . were then able to distinguish between precipitates and mere color changes. Consideration of these various reactions led the students naturally to some simple qualitative analysis. The next class session was devoted to the exploration of these ideas. The students attempted (usually very successfully) to distinguish among six bottles containing sodium, barium, lead, copper, or nickel ions or pure water. Those who finished this could try hottles which contained acetate, sulfide, sulfate, carbonate, or chloride ions. This second part was much harder as it required them not only to draw upon what they had done in the previous class hut also to go hack a week and a half to their notes on what had hapnened when acid was added to various solutions. Less successful was the next portion, attempted by only a few of the older students, in which each unknown contained two catVolume 52. Number 11, November 1975 / 737
ions. Testing for one substance in the presence of another was more than all but a few could grasp. A demonstration of some oxidation reactions occupied most of the following class. The usual substances were used: wood splints, steel wool, sulfur, etc. Our feedback from the students was that they were not happy to sit passively watching someone else performing experiments; they had had a taste of working on their own and were sorry to lose it. Because of this, we abandoned the demonstrations of plating and of electrochemical cells which we had planned for the next session. Instead, each student ohserved what happened when steel wool was immersed in a solution containing cupric ion and when copper foil (cut into fancy shapes) was immersed in a solution containing silver ion. In order that they could test for ferric ion in the solution in the first case, they were told about the red color which results from the reaction of ferric ion with thiocyanate ion. Most were ahle to decide that the use of ammonia would indicate whether cupric ion was present in the second case. The solutions had been tested originally to confirm the absence of ferric ion and cupric ion. We developed equations for these two reactions and for some of the oxidation reactions performed earlier, e.g., those of carbon, sulfur, iron, with most of the students understanding what was going on. For the last day of class two activities were planned. The action of an oxidizing agent on a starch-iodide solution was
738 / Journal of Chemical Education
demonstrated. The students were told that if no blue color appeared, then the material under test was not an oxidizing agent. They tested CloroxQ (diluted to -0.25% NaOCI), Come@, and a diswashing detergent to see which could he classed as oxidizine aeents. The second activitv consisted of dividing the class r&domly by month of hiithday into two teams for several contests in the lecture room. Several games were used, beginning with asking for the element's name when given the symbol and working up through "Who am I?" (I am a gas which smells like rotten eggs, etc.) to naming a reagent to distinguish between two substances. As a whole the students were extremely well-behaved, faithfully wearing their safety glasses and performing only the suggested experiments. We did have some difficulty with two students who tended to leave the laboratory at odd times and wander through the building. The opportunity to reflect on one's sins while sitting in a lonely hood may he unsound pedagogically or psychologically, hut it was undeniably effective. Our overall assessment of the program is that 15 of the 17 students and all of us enjoyed it. The older children, in general, could reason better than the younger, hut there were some startling exceptions to this. Most of those in the course will he ahle to approach either a future course or more mundane situations with a somewhat better idea of how a scientist would act.
