James Bryant Conant Award in High School Chemistry Teaching
Some Things Have Changed Little in the Last 138 Years Ronald I. Perkins Greenwich High School, Greenwich, CT 06830
I t is a great honor to receive the James Bryant Conant Award in High School Chemistry Teaching. I am especially pleased to be a part of this Chemical Education Awards Symposium which includes Henry A. Bent, Roald Hoffmann, George C. Pimentel, and Bassam Z. Shakhashiri. This is the first time that both the recipients of the ACS Award in Chemical Education and the ACS James B. Conant Award in High School Chemistry Teaching are part of the same awards svmnosium. ~ e c e n i l y , ' Idiscovered, a t the Memorial Library of the University of Wisconsin-Madison, a marvelous collection of 21 chemis&y lectures which were compiled into a book, published in 1848.138 years apo. This book, entitled "Chemistry No Mystery or A ~ e c t u r e r ' sBequest", was written by John Scoffern, a professor of chemistry a t the Aldersgate School of Medicine in England. I t seems to be based on a series of summer lectures that Scoffern gave to a group of young adults while thev were on holiday. I have found chat much of thematerial contained in these lectures is timeless and could equally well be presented today. Also, I am convinced that Scoffern was a master teacher and that his students were little different from those currently enrolled. This afternoon I plan to share with you parts of these summer lectures and intersperse some i f m y own observations about chemical education and good teaching in general.
reduce all of educational psychology to just one principle, I would say this: The most important single factor influencing learning is what the learner already knows. Ascertain this and teach him accordingly." In other words find connections between the chemistry and the real world of the student. I still remember much of the descriptive chemistry that I learned from Harold Iddles 29 years ago at the University of New Hampshire because he, too, connected the chemistry to real life examples. He told the story of a circus coming to a nearbv town. The advance oeoole from this circus asked the store owners if they cou~d'~l;e posters to their storefront windows. After the circus left, the store owners found that the glue could not he removed from the glass and asked Professor Iddles for the name of a good solvent. The store owners, alas, had to be told that the circus people had used water glass, sodium silicate, as a glue. This had reacted with the glass in such a way that no solvent could possibly help. Great teachers seem t o be able to conned their subject to the student's real world. One of the ways of connecting chemistry to the student is by using classroom demonstrations.
Scoffern Began HIS Course wlth Enthusiasm If I were to present myself before you with an offer toteach you some new game:-if I were to tell you an improved plan of throwing a ball, of flying a kite, or of playing at leapfrog,oh, with what attention you would listen to me! Well, I am going to teach you many new games. I intend to instruct you in a science full of interest,wonder and beauty; ascience that willafford you smusement in your youth, and riches in your more mature years. In short, I am going to teach you the science of chemistry. ( I )
Sound familiar? Manv of us todav still demonstrate the solubility of ammonia in water. In fict, a sketch of the ammonia fountain is found in almost everv chemistrv text from 1850 until 1920. Those who examine old chemistrv texts discover that until about 1920 the textbooks were filled with interesting sketches of simple demonstration apparatus. No doubt, these sketches provided students with the seed for much experimentation in the laboratory. Beginning, however, in the
Wow! What a powerful beginning-"A science full of interest. wonder and beautv". There should be no auestion in anyone's mind but that scoffern loved his subject, chemistrv! And. i t is easier and certainlv far more exciting to learn frbm a teacher who enjoys his subject. Just like Scoffern, we too must show students our enthusiasm for the study of chemistry. Enthusiasm is contagious! HIS Lecture Material is Reievent If 1 drop alittle hartshorn,or solution of ammonia in water, into a solution of a salt of copper, the mixture immediately acquires a deep blue tinge; in this manner we may detect the presence of copper in pickles, which are frequently adulterated with it in order that they may preserve a green eolour. How foolish to mix a slow poison with an article of food merely for the sake of imparting an agreeable colour! (2) Scoffern, as with all truly great chemical educators, made the chemistry relevent to students by relating it to real life examples. Years later David Ausubel(3) wrote: "If I had to
Scoffern Used Many Simple Demonstrations I now invert a bottle full of ammoniacal "eas under water and shake it well; havmg prev~uuslyremoved the glass plate. Spe how the water rushes up and entirely f i l l , the bottlr.This experiment teaches ur what a very great aifinity, or desire to umte ammonia and water evince for each other. (4)
Ronald I. Perkins. Senior Chsmistq Teacner a1 Greenuoch High School in Greenwicn. Connect.cul is the reclpiem of the 1986 James Bryan! Conant Award n rl gh School Chemislry Teaching. Since graduating from the University of New Hampshire wRh a BA and an MST Degree, he has been recognized as a Cornell Shell Merit Fellow, a 1982 Dreyfus Master Teacher, a I s 8 3 Presidential Awardee for Excellence in Teaching Science, the recipient of the 1984 Regional Manufacturina Chemist's Award. and the recioient of the 1985 Normeart ~~-~ Reg onal ACS Award For !he p a n tour years ne has collabaraleo w ln Bassam Z Shakhashirl ol me University of Wisconsin-Maomon on a var ery of cnemical educal8on programs nc ud ng the Chem ca Oem Onswation Handbmk Series. He has also collaborated with Babu George on a number of chemical education projects at Sacred Heart Univernity in Connecticut. In Me past two years he has oresented mare Man 75 demonstrationsessions for teachers and stud& in 24 states. This PaPel was presented at the 191st National Meeting of the Americanchemical Society in New YorkCityduring the Chemical Education Awards Symposium. April 1986.
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1920's most authors replaced the sketches of demonstration apparatus with photographs of industrial buildings and equipment, photographs where the actual chemistry is mostly hidden. I suspect that for purposes of teaching chemistry, the sketches of demonstrations are far more valuable than the glossy photographs in which the chemistry is hidden. We often seem quick to substitute new technology for older more proven practices. Today, although the computer can be a powerful tool, we should be wary of substituting computer simulations for actual lahoratory work. Scoffern's Lectures Contain Descrlptlve Chemistry Mercury, or quicksilver-This very curious metal, being always liquid at common temperatures; although by intense cold it may be frozen,and when solidified it is malleable. In the neighborhood of Hudson's Bay, this metal has been beaten out into leaves as thin as paper. (5)
Such an interesting wav to teach descrintive chemistrv. Instead of simply stating that the melting point of mercury is -39 O C , in these few sentences he teaches about the properties of mercury in a memorable way. Liquid at room temperature, it freezes a t Hudson Bay temperatures and is very malleable when frozen. I am left with an image of someone pounding mercury into a leaf in the hitter cold temperatures of Hudson Bay. Today, there seems to he general agreement among chemical educators that more descriutive chemistrv,. should he taught. 1 agree. But how tu make it interesting and rele\.ant. that is tlie challenae! 1 hone that when educators steo onto the descriptive chemist6 bandwagon they don't mkan to have students simply memorize that chlorine is a nale greenish-yellow gas, sil& chloride is a white solid, an2 ammonia dissolves in water. The teaching- of descriptive chemistrv can and should he made exciting. As much as possible, students should learn descriptive chemistry from actual observations of chemicals in the laboratory and in classroom demonstrations. We tend t o remember more of the chemistry that we have actually ohserved and sometimes we even discover something unexpected. What could he more exciting than for a student to observe something that others in the class have not noticed? Wow! I hope that proponents of teaching more descriptive chemistry don't mean to replace theory with descriptive chemistry. As Frank Pilar wrote (6):"Damn the permanganate volcanoes: full principles ahead! . . . Today's theories have done a truly remarkable job in making chemistry a much more rational subject, and any step to abolish them from the curriculum would be a step backwards!' I n my opinion we should teach both descriptive chemistry and theory. In this way we can encourage students to use chemical principles t o explain their observations. Descriptive chemistry can even he used to create challenging problem-solving situations. One way of doing this is to ask students to analvze a situation in which a number of previously observed Ehemical changes have been combined into amore complicated problem. The students can he asked to record their observations carefully and to predict possible starting chemicals. For example, after students have studied the reaction of copper with concentrated nitric acid and the reactions of acids with bases usinn phenolvhthalein as an indicator, I ask them to analyze mythree-flask, "coin-operated" demonstration (see figure).' ,, I he apparatus consists of three flasks containing unequal amounts of clear, colorless liquids. The flasks are connected ~~
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This demonstration was developed by Ronald I. Perkins with the assistance of Karen Spencer while both were on the staff of the Institute for Chemical Education, University of Wisconsin-Madison. June 1985. 782
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When copper coins are added to a lhree-flask system containing unequal amounts of colorless solutions, a number of visual changes occur. After 15 minutes the solutions in each of lhe I Iflasks are equally distributed and appear red, white, and blue.
by glass tubing inserted through rubber stoppers as shown (note the position of the tip of the tubing relevant to the liquid level in each flask). To initiate the reaction, I lift the stopper on flask #1, drop in two copper coins, and then quickly stopper the flask. A brown gas is produced and then disappears as it bubbles into flask 2, liquids flow from one flask to another, colors of solutions appear and sometimes disappear, and the flow of liquid from one flask to another reverses. After 15 minutes the three flasks contain approximately equal volumes of liquid in the patriotic colors of red, white, and hlue (in flasks 3, 2, and 1 respectively). What was originally in the three flasks? For the benefit of the reader, flask 1contains 25 mL of concentrated nitric acid; flask 2 is completely filled with 0.10 M nitric acid along with a few milliliters of phenolphthalein solution; and flask 3 contains 0.35 Msodium hydroxide solution. I have learned from my students that the same colors can he produced if the contents of flasks 2 and 3 are switched and the concentrations are changed. Descriptive chemistry can be used very effectively to encourage critical thinking. John Scofferu over 140 years ago enthusiastically taught descriptive chemistry. Today, we too must strive to teach these chemical facts in a manner that is both interesting and challenging to our students. Another appropriate place to learn descriptive chemistry, however, is from observations in the laboratory. Good Laboratory Experience Is a Must How, then, would you dry a small-neckedbottle? I will tell you. Having made it warm, insert a tube like this, and suck out air from
the bottle several times, by which means moisture is also sucked out, and the bottle dried. [SafetyReminder] If this moisture be injurious, of course you would take care that it might not get to your lungs, but you would performsuction by means of themauth alone. (7) Notice that, although Scoffern was interested in Safety, his lahoratory experiments were not risk free. He taught his students how to work safely with potentially harmful materials. We should do likewise. Instead of simply removing the mercury thermometers and Bunsen burners from the laboratory, as some advocate, and avoiding the use of dilute solutions of lead ions and chromate ions, as others advise, let us teach ways of safely using lahoratory equipment and chemicals. The laboratory is a very important component in the learning of chemistry, but in many secondary school chemistrv courses it has all but disanneared. Over the last few decades there has been an erosibn of actual lahoratory time built into students' schedules. School administrators have found that students can still achieve well on national multi-
ple-choice examinations without the costly laboratory component. I believe that this is an indictment of the narrowness of these examinations as well as the lack of adequate testing for knowledge aained in the l a b o r a t o ~In . manv areas of the country the-double laboratory peridds, common 20 years ago, have been discarded. In todav's 45-or 60-minute class pt'riods, it i~almostimposiihle togivestudents a meaningful laborntory rxprrienre. Students must nice the brll to obtain materials, complete a short, stepwise exercise, and then clean up. There is little time for discovery or to think about the experiment. The thrill, joy, and satisfaction of learning chemistry are denied. A set of ACS recommended guidelines for the teaching of secondary school chemistry may be valuable. These guidelines could include such items as recommended qualifications for secondary high school teachers, a list of recommended experiments and a suggested number of hours of laboratory and classroom time. The guidelines might even suggest that chemistry teachers be given released time to prepare laboratory materials. The recommendation's standards should be set high. Those schools that are able to achieve these recommendations could he given the status of having an ACS-approved chemistry program. This may give us iust the lever we need to affect chanee in our chemistrv Whatever the method, we need to find ways encourage schools to maintain the laboratory component of their science courses. I am especially concerned with the growing tendency to teach advanced placement chemistry courses without the lahoratorv component. It is disturhina to find that manv teachers have fi;und that they ran pre& their studrnts t" take the riroruus Erluvarional'l'esting Sewice APChemistrv ~ x a m i u a t h nwithout giving students the opportunity Lo work in the laboratory. This is wrong. T o offer a legitimate advanced placement science course, a laboratory component is necessary. One solution to this problem is for colleges to give Advanced Placement credit in two parts. Colleges should grant advanced placement lecture credit to those secondary school students who achieve well on the written examination. However, colleges should give credit for the laboratory component only to those students showing evidence of actual laboratory work. I t might be feasible to devise a mechanism for evaluating student laboratory skills similar to the "o"leve1 examination used in England. Another solution, though cumbersome, is to grant credit for the on the hasix d a n inrerview u,ith the I a b n r a t t ~ rromponenr ~ student und upon examination of his secondary schtwl 1nl1oratory notebook. It is important for AP chemistry teachers to he given the message that the laboratory is an important component of the course. Discourage the Making of Exploslves
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With chlorine and iodine. nitroeen forms two most daneerous compo~mdi;the ~llghtesrt m ~ CAIIWS h a violrnt cxploai~n;once made, rhcy cannot be hnndled and n person is nrvcr $air when the) arc nrar Monsieur Ampere. the d~snwerofrhloridr otnirrogen, lost an eye and a hand in prosecuting his experiments on it: and two accidents by the same substance have come within my own personal observation. Under these circumstances I shall not teach you how to make either the chloride of nitrogen or the iodide of nitrogen. (8) ~
This is certainly good advice even t o this day. Although some students seem to be instinctivelv drawn to the makine of explosives, and many associate the subject of chemistry with exolosions, I suaaest that we can better direct the attention of our times when we use explosions in our demonstrations, it seems more alchemy than chemistry. Although many chemical educators use potentially dangerous demonstrations in their own classrooms under carefully controlled conditions, some bring these same materials to our elementary schools when invited to present a chemistry lesson. I t is not unusual t o hear of chemical educators
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using chemicals such as nitrogen triiodide or peroxyacetone in these presentations. This is imprudent. The risks to students and chemical education are too great. Each accident results in a cry from some to stop all chemical demoustrations. Work with explosives encourages dangerous home experimentation. At the very least we are leaving the elementary students with the idea that chemistry is more magic than science. I suggest that when asked to give an elementary school presentation it is far more appropriate to teach simple concepts using safe materials. Scoffern, 138 years ago, was a master at using simple demonstrations to teach chemistry, and he clearly recognized his responsibility when he said: "I shall not teach you to make either the chloride of nitrogen or the iodide of nitrogen." Still good advice. Encourage Students to Learn Nomenclature John Scoffern seems to have anticipated student difficulties and addressed the problems directly. T o encourage his students to learn nomenclature he said: Rememher a child does not derive much pleasure in learning his alohabet.vet it would beaoitvindeed that he should be debarred frbm all the riches of literaiurk and science, merely because of the annoyance to be endured in first learning his letters. (9) In order to use higher mathematics, students have to have learned a set of addition and multiplication facts. One does not have time to derive 7 X 7 whenever it is needed. In the same fashion, in order to learn chemistry successfully, the ions and a few nomenclature rules must he memorized. Without learning this information, it is difficult for a person to perform even simple tasks in a first-year chemistry course. Although it is difficult to convince students of this, it will make the learning of chemistry far easier. In my own class, to emphasize and encourage the learning of chemical nomenclature, every test contains 10%nomenclature. Scoffern was a very perceptive teacher; he anticipated that students would have trouble learning nomenclature, so he addressed the issue directly. This reminds me of another great teacher, Nobel-Prize-winning Roald Hoffmann of Cornell University. Last year while I was on sabbatical at the University of Wisconsin, Hoffmann gave a series of lectures on the chemistry of the solid state. I attended these lectures and was thoroughly impressed with his teaching style. In these lectures, he made the complex seem simple and often stopped and reviewed that which he had just taught. He often would say: "Now this is where you are apt to get lost, let's go over it again . . . Let's make certain we understand this concept before going on." Great teachers seem to have this ability to anticipate student difficulty in understanding. Practical Appllcatlons are Important Including practical applications in lessons seems to get the student's attention and Scoffern was a master at getting and keeping students' attention. A person may have swallowed oxalie acid, which in a few minutes will certainly kill him, if remedies he not at hand. Oxalic acid when combined with lime is inert; but lime, too, is a poison; give them some form of earhonate of lime: run to the kitchen for some whiting; get a lump of chalk; or if neither he at hand, quickly knock down a piece of the wall, and administer it mixed with milk or water; do this immediately and the individual is certainly saved; but wait a few minutes, and he as certainly dies! (10)
One can probably not find a more practical application of a chemical concept. We Don't Have Time to Cover Everything1 It would neither he very instructive nor very easy to go through the process of making the different ethers: none of them are of much importance,with the exception of sulphuric ether, [diethyl ether], but the latter demands little attention. (11) Volume 63 Number 9
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Obviously, Scoffern was not greatly interested in teaching the suhjectpf ethers and chose to leave it out. All chemical educators have this same problem of too much to teach in a finite amount of time. We must he selective, however, about what we include in our courses and avoid giving students a false sense of understanding by simply mentioning many different topics. Whatever we teach, we should teach it well.
in every frolic, so we found chemistry; but as it grew up to its full size end farmidahle strength, it became a thing no longer to he played with;-demanding all care, attention, and respect. If I have grown dull in the prosecution of my task; if I have been less interesting hy the termination than the commencement of my lectures, do notjudge me too harshly, I beseech you, hut attribute some of these defects to the increasing difficultiesof my subject. (22)
Concluslon
John Scoffern seems to have been a very wise, perceptive teacher who well understood his students. He began his course with enthusiasm. In his lectures he connected the chemistry to the student's real world. His lessons were filled with simple demonstrations and practical applications. He emphasized safe laboratory techniques. He also realized that one could not teach everything in a single course. Apparently some things have changed little in the last 138 years. Listen to the words that Scoffern used a t the end of his summer course. We entered upon the study of our science with sportivenessand mirth; but towards the conclusion of our lahours we have been compelled to become more serious, and to use language more in accordance with the nature of the subject. As a young lion torn from the forest is tame and playful, allowing caresses, and joining
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Acknowledgment I thank the Ethyl Cooperation for sponsoring the James Bryant Conant Award.
Literature Cited 11) Scoffern.J. "Chemistry No Mystery or A Lecturer's Bqueat". 2nd ed.; Althur Hall: London. 1848: D 1. 12) Ref 1 , p 172. I s ) Ausubel. D. P:'Educational Psychology. A Cognitive View", 1st ed.: Holt. Wnehart. and Winston:NewYork, 1368:p ui. 141 R p f l . 0 171.
