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curriculum report
GRACE FISHERMCGUF~E
Nodhwestern High School Hyattsville, Maryland 20782
Chemistry Is Fun A Laboratory Program Designed for Inquisitive High School Students D. Yaniv, H. Heled, and M. Ariel Technion, Israel Institute of Technology. Haifa, Israel About a dozen years ago, the Extension Division of the Technion, I.I.T., initiated science programs designed to attract young people. Until recently, these programs consisted mainly of lectures presented by scientists specializing in certain well-defined areas. Gifted science-oriented students were admitted mainlv a t the iuniorhenior hieh school levels. although a few c&rses weie also offered to elementary school nunils. The list of courses eiven in anv vear was circulated in schools and the youngsterH were free% choose whatever appealed to them most. In 1979, the first lahoratory course was added to this fist, with chemistry as the chosen discipline. This immediately was in great demand hut was limited by space restrictions to 20 participants per course. A mixed group, in both prior preparation and age (1&17), arrived and took part in a 23-week, 2-hours-per-week laboratory course. The schedule followed each week included a review of the results obtained the week before. This review was followed by a discussion of the exneriment to he conducted. and finallv the experiment itself h a s performed. Concise hondouts detailing the theoretical hasis of theexperiment planned for the This featuremest gales aspens of me seconaav schoo chem stv cunrul.m and related Rlpm New aevelopmem will be #ntrod,cedand estaolmed tecnnlques crmquea Contr b~loonsare welcome
coming week were handed out weekly. Since the whole program preserved student self-motivation, no quizzes or formal exams were held. Throughout the program students were encouraged to plan their own experiments. Goals The principal objective of the program was to drvelop the interest of talented . youngsters in scientific activity. Although . secondary, the following goals were also kept in mind. 1) Encouraging scientific thinking through open-ended experi-
ments. 2) Allowing youngsters access to common chemical instrumentation
(pH-meters,spectrophotometers,etc.) and introducing them to a number of basic laboratory techniques (weighing, measuring volumes, etc.). Detailed Course Program The course was divided into two sections: I-General and Inorganic Chemistry, and II-Organic Chemistry. In the fust, the students learned routine lab techniques. Experiments in the second were planned to include familiar materials which are essential to the survival of living species (sugars, proteins, vitamins, etc.). Evaluation Acquaintance with concepts, areas, and techniques related
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to chemistry aid students in deciding which direction their future studies should take. How many of them will indeed take up chemistry or related subjects will be revealed only in the years to come, in a follow-up to he carried out on the participants of this course. Most of the other objectives specified above have been achieved. One of the most interestine facets of the course was the aspect of self-planned experiments. Due toditferena.~in chemical hackground and individual capability, some participants attcceeded where otheru failed. The basic knowledae cuntained in the rourse lecturrs. theoretical backgroundmaterial, experiments, and disc&ons encompassed mauv aspects of chemistrv and amused interest in mole advanced and specialized courses (dealing with chemical instrumentation, chemical analysis, polymers, hio. . chemistry, etc.). Since the course took place in a university lab, students had direct access to simple chemical instrumentation (pH-meters, conduetometers, and single-beam spectrophotometers), in addition to being exposed to demonstrations involving sophisticated equipment (atomic absorption spectrophotometers, double beam spectrophotometers, gas chromotographs, polarographs). The meetings dedicated to building models in organic chemistry2 helped students toward an understanding of molecular structures and gave them an idea of stereochemistry. In the bingo game4, which was enthusiastically received, students become acauainted with the ~ e r i o d i ctable and common chemical elements (37 elements were included in the eame). These elements were descrihed hv data learned durine the course and based on familiar uses of the elemens (Sn was defined as an element used in welding; HE as a liauid metal a t room temperature, used in therm&ne&rs, etc.) Besides playing the game as descrihed by Swan," smaller prizes were added for those first filling a line or a column in the table, while emphasizing the chemical features common to those elements.
tinued for another semester and developed a liking for chemical suhiects and lab work. Introducing novel techniques raised curiosity, and even if the students could not alwavs understand the whole theoretical background of the subject, it opened a window to their future interest in chemistrv. Every one of the participants is a goodwill messenger to chemistry in his high school and his neighborhood.
Limltatlons The maior limitation of the course was time. The need to include thk discussion of the previous experiment, as well as the exnlanation and ~erformanceof the current lab e x ~ e r i ment, ;n the two honk allotted to each meeting made for a verv. tizht .. schedule. restrictinz choice of lab exwriments. The precision of the results often had to be sacriiiced: studenrs used half-analvtiral instead of analvtiral balances, measurina cylinders instiad of pipets, and ;;(;on. Hecause of the s h o ~ t time alluwed for discussion 1,f the theoretical hackan~und, some participants performed part of the experiments without reallv understandinz their theoretical basis k-a s chromatoeraphy, conductometry, complexometry, spectrophotometry, etc.). Another partial limitation of the cuurse arose from thedesire to allow students to plan their own experiments. Some of the ex~erimentsfailed because of inadequate ~ l a n n i n-.ee.e., :some students failed to separate mixtures into components. These neeative results were later used to discuss the correct way for designing and performing the experiment. The performance of the experiments hy students working in pairs often had a detrimental effect: in many cases the more active student did most of the work and thus profitted most; in others, activities were divided so that each did only part of the work.
Week Tmic ~ ~ - . 12. 13 Introductory lecturer in organic chemistry using 14 Starch-qualitative identification, extraction Com
Summary The relaxed atmosphere in which the course was conducted added to its attraction. Some students drove 50 km after school to come to the lab; participation was full and drop-out rate zero. The friendly relationship among the students proved an additional factor for encouraging full participation in the weekly meetings. All graduates wanted the course to he con-
Reilley. Charles N., and Sawyer. Donald T.. "Experiments for Instrumental Methods," McGraw-Hill Book Co., Inc., N.Y., 1961, p.
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870
Journal of Chemical Education
Acknowledgment Thanks are due to the Department of Chemistry of the Technion, I.I.T., for partial support of this experimental course. Section l-General and Inorganic Chemistry Week Topic of course obiectives and laboratow Introduct(~~ le~t~redisC~s~ion Safetyreg" at ons Anract ue oemanstrat ons chosen from a varlsty of chem ca experiments as tncenttves for m e cont~nuedetlart required in keeping up with the course. Laboratory tools--determination of weights and volumes. Acid-base titrations, using indicators and pH-meters. Titrations of materials encountered in everyday life--acetic acid, ammonia, etc. Spectrophotometry-qualitative and quantitative application to solutions of various oalored salts. Separation of a mixture into its individual components. Lecture-discussion winding up meetings 2-5, following by an intrcduction to meetings 7-8. Ion exchange'-cation separation monitored by their identification. using spot tests. Water deizafm-mcmitwed by tmductivm,md pH measurements, taken before and alter the deianization process. Electrochemical cells-migration of ions in the electric field,water electrolysis. Paper and column chromatography-sepration and identification of some components of commercial gasoline. ~
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Sectlon Il-Organic
Chemistry
potatoes, unripe fruitsand saliva, and the hydrolysis of starch. Di- and monosaccharides-tests for common saccharides-sucrose, lactose. maltose, glucose, fructose and galactose-sweetness. silver minor test. Eenedict lesl, and carbonizalion. Roteins-identification of some proteins by wiw reactions, general (biuret, ninhydrin) and specific (Millan. xenthopratein, sulfurtest, denaturation and absorption spectra). Vitamin C-quantitative determination of vitamin C by titration with 2,6diehlarophenal indophenol. The vitamin C originated from different sourcespur8 ascorbic acid, various citrus fruit juices (orange,lemon, grapefruit),citrus iuioealtex heatirrg. pre-ed juice. etc. Lipids-synthesis of soap fmm fata3-later stability in hard and salt water. Polvmers--lectureand denanstratiom-poiy~ylene.tkmmning and thermoplastic polymers, nylon. Forming objects from Perspee. Muiiidiscipline experime~-determiMtim ofC P in aqueaus solution using various analytical techniques: titration with EOTA, Indirect titration with KI, spectrophotametry. dectrogravimetry, and Ion exchange. Bingo-the periodic table.' Farewell parly.
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268.
Vaniv, D., Heled. H., and Ariel, M.. "Using Models in undergraduate E~uc. students course." note submitted to J. CHEM. Muhler. Joseph C.. Rohrer. Charles S., and Compaigne. Ernest E., "Introduction to Experimental Chemistry." The Xerox Cwporation. 1972, p. 181.
Swan, R. J., The School Science Review, 59, 121 (1977).
