Building a Chemistry Program that Fosters Independent 77hking William B. Robertson East Mecklenbura Hiah School
charlotte. NC 28212
For tht. past twenty-twc, years, I have taught advanced first n n ~ ~l r m n , i - \ . e :chemistrvclasses ~r at East \Iecklenburt!- Hiah School, a comprehensive, college-preparatory school with a current enrollment of sliehtlv more than 2.100 students. r ~located in a highly Founded in 1950, East ~ i c k i e n h u is professional residential area. Since Charlotte is known as the textile center of the South, our chemistryprogram has always enioved a hieh incidence of students from chemical and en* gineering backgrounds. Initiallv. the onlv chemistrv course offered a t East ~ecklenl;& was Chkmistry I, open to any student who registered for the course. The classes were extremely large and the available laboratory equipment was very meager.There were two chemistry classrooms, one of which was suitable for limited lahoratorj work. As a result of some very hard, enterprising, and cooperative work on the part of Dr. William E. Cheek (presently with Central Piedmont Community College) and I, the popularity of the chemistry program grew quite dramatically. After two years, chemistry was offered a t two levels, Chemistrv I-Reeular and Chemistrv I-Advanced. The advanced c o k e originated with the tr& programs of CBA and CHEM Studv. both of which were taught a t East Mecklenburg. The CBA program was dropped after two years, and I turned completely to CHEM Study. Following the finalization of the trial CHEM Study program, I have used various revisions with much success. However, our current advanced first-year course is a hybrid of the best of CHEM Study, CBA, Nuffield. and the old descriptive chemistry program. In the fall of 19'58,a group of science-oriented seniors, having comnleted all available courses in the science curriculum, requested additional work in chemistry. Out of this student need, two additional chemistry courses were developed. The first was Chemistry 11, an advanced, college-level offering meeting double periods daily and developed to meet therequirem&ts of the Advanced Placement course. The course is currently designated as Chemistry II-AP and all students are asked to take the AP test. However, some students could not afford a double period in their advanced oroeram. To meet this end, an independent study, laboratory-oryented, one-hour course identified as Chemistrv Problems was introduced. Students in this course select qualitative and quantitative analysis, a research project, or a series of special laboratory. experiments based on student interest. The dramatic increase in chemistry enrollment, coupled with the performance of our students a t the college level, re-
.
~
~~
William B. Robertson is Chairman of the Physical Science Department at East Mecklenburg High School in Charlotte, North Carolina. He received his BS from Kansas State University and an MS from both Oklahoma State Universityand the University of Virginia. He has received many awards for his teaching, including the Conant Award in 1970,the Manufacturing Chemist's Association Award in 1977,and the Outstanding Chemistry Teacher Award, Carolina Piedmont Section, ACS in 1961 and 1970. He has heen active in the Carolina-Piedmont Section of the ACS, serving as its chairman in 1970. He is best known for building a strong and diverse chemistry program in his school, and he talks about some of the philosophy underlying this project as well as his concrete teaching techniques in this View. 670 / Journal of Chemical Education
sulted in the completion of a chemistry suite in 1964. The suite arrangement consists of four well-equipped, self-contained laboratory classrwms surrounding an independent study and teacher research facility. A departmental library, chemistry office, two large storage rooms, and a team teaching room complete the original complex. Each lahoratorv-classroom is desiened for a maximum of twenty-four studehts and contains 168 fully equipped student lockers. I am firmlv convinced that the suite arranaement is the most efficient facility for teaching high school chemistry. T o me, the teaching of chemistry is a most fascinating and challenging enterprise. I never cease to be amazed at the advances in high school chemistry since my high school textbook ("Practical Chemistry,"Black, N. H. and Conant, J. B., The Macmillan Company, 1927) and a current popular text such as the latest edition of "Foundations of Chemistry" by Toon and Ellis. I consider i t my responsibility, as a teacher of chemistry, to present in an intelligible and interesting manner the fundamental chemical and physical concepts of the discipline, not as an end in themselves, hut as a means of understanding the interdependence of man and the material world about him. To this end, my teaching activities are directed to provide a relevant learning atmosphere which stimulates curiosity, creativity, logical reasoning, and independent investiga~. tions. At the very outset of an introductory course, i t is my enof the i n . ~ u. iw deavor to instill in each student an aooreciation .. method of chemistry with timely and relevant demonstrations and laboratory activities. Concurrent with this goal is the development of enthusiasm- and a sense of pride and achievement while teaching chemistry as it is practiced today. I do not have a specific recipe for the successful teaching of hiah school chemistrv, but I would like to share some of the that have c&rihuted immeasurably to the success of my program. I try to make full use of performance objectives in the introduction of each fundamental concept. I have come to consider this practice a prerequisite to a successful course. It appears to me that better results can beatt;iint.d if thestudent knows what is expected of him from the very outset of each unit. I introduce my first-year advanced course with a series of demonstrations designed to motivate the student and a t the same time to emphasize the importance of accurate observations in chemistry. Students are required to record their ohservations amidst challenging questions. This activity is really our first laboratory exercise. At the conclusion of the demonstrations. each is reviewed and questions are entertained. The metals lithium, sodium, potassium, and calcium are inspected and then reacted with cold water containing a few drops of phenolphthalein indicator. T h r students &nerallv note thedifferences in rhe ratenf reactions, but they are more fascinated by thr mrtali which float on water. Metallic zinc is reacted with concentrated hydrochloric acid producin:: a colorless eas liehrer than air. This is followed hv tht: reaction " of copper metal with concentrated nitric acid producing a colored gas heavier than air. A sample of ammonium dichromate is passed around the class and the students are asked to note and record the physical properties of the compound. They arc nlsu asked ru carefully read the label and to note the safety precautioni. A
-
sample of the compound is ignited on an asbestos hoard and the students are asked to record their ohservations. Bottles containing equal volumes of mercury and distilled water are passed around the class for student ohservations. Twenty-five milliliters of concentrated sulfuric acid is added to 100 ml of water in a 250-ml beaker and the initial and final tempetatures are noted. Solid ammonium nitrate then is dissolved in water and the temperature change is noted. This demonstration introduces exothermic and endothermic terminology. Students greatly enjoy this approach. I t "turns them on" and creates a great deal of discussion the very first meeting of class. Their curiosity has been aroused, the ice has been broken, and we are off to a good start. Other demonstrations are used as time permits in this initial meeting. Other demonstrations are available to draw from, but it is imperative that each demonstration he carefully chosen for a particular purpose. I want t o avoid a chemical magic show. Early in the lahoratory program, I try to engage students in exercises that involves logical reasoning. One such experiment is the density-specific gravity determinations. Following the usual activity using regular and irregular shaped samples of pure metals and alloys, a solid irregular-shaped sample which is lighter than water is introduced. The students are asked to develop a procedure for determining thedensity and specific gravity of the specimen. At this point, I inform them that they will he called upon in several future experiments to develop their own procedures. This practice makes most students procedure conscious in future experiments. Far too many lahoratory experiments in the beginning courses are strictly manipulative and the only challenge lies in the accuracy of their results. Basically, most students enjoy being challenged to develop procedures to he used in extensions to many of the experiments included in the first-year chemistry program. The laboratory preparation of oxygen provides another such opportunity. I first demonstrate the preparative procedure which involves the uncatalyzed thermal decomposition of potassium chlorate. I tell the students that this reaction is far too slow, and I solicit suggestions for improving the rate of reaction. The ensuing discussion introduces the term catalyst, and someone who has read the assignment suggests solid manganese dioxide. Students then return to the laboratory table and one pair gathers data on the uncatalyzed reaction while the other pair gathers data on the catalyzed reaction, each using identical masses of potassium chlorate. Data is exchanged and a graphic presentation of the data is required. The students are then asked to locate the element manganese in the Periodic Table and t o identify the orbital group to which it belongs. I suggest that since manganese is a 3d transition metal would i t he logical to assume that the oxide of some other 3d metal might catalyze the reaction. Eventually, the use of ferric oxide (formerly used as the catalyst in the lahoratory preparation of oxygen) is suggested. The experiment is extended using ferric oxide as well as a few other 3d metallic oxides and the results are compared graphically. Frequently, I ask the class t o consider the other oxychloro compounds of potassium as sources of laboratory prepared oxygen. Upon completion of a literature assignment, potassium perchlorate is brought into the experiment and compared with potassium chlorate. Further study brings the entire sequence into the light of the law of multiple proportions. I t also provides a good opportunity to introduce the nomenclature of the oxychloro compounds as well as the safety requirements of the chlorates and perchlorates. Far too many students never challenge or question what they read in a textbook, They have accepted the textbook as factual information, yet textbooks contain errors. As a part of the preparation of oxygen lahoratory experiment, the stu-
dent is asked to record the physical properties of their sample. A chlorine-like odor is often re~orted. ..vet notassium chloride is the only chlorine containing product appearing in the halanced equation and i t is odorless. The students are asked to challenge the validity of the balanced equation as it appears in the textbook. This provides a wealth of activity and interest and even draws some parent chemists into the problem. If a meaningful exploration of the fundamental concepts of chemistry in the lahoratory is to he effected, a generous infusion of relevancv is hiahlv essential. In light of local recycling activity of ~ k y n o l d ~s l u m i n u mI, ask ihe students to hrina to class an aluminum heveraae can makine no reference to th;, intendrd use oithc can. (5l;mewhat gre&r interest i, mal~it'estrtlif you call for 3n .~luminumIwer can., Some uf the cans brought& are not of aluminum construction, totally or in part. I find that some students have the mistaken idea that allheverage cans are of aluminum construction. Therefore, the initial learning activity in the lahoratory svnthesis of ootassium aluminum sulfate centers on beveraee can construction. The actual lahoratory experiment is a great multiple purpose activity focusing on the following:
.
-
1) Stoiehiornetriecalculations
2) Theoretical and percent yield 3) 4) 5) 6)
Crystallization and recrystallization techniques The melting paint as an index of purity Crystal growing techniques Introduction to double salt chemistry and nomenclature
After aradina the student preparations, the samples are combined andused in the growing of some large alumcrystals. This is perhaps the students favorite laboratory experiment in our present program. Counsellina has been an important activity in my chemistry teaching. Active participationin the activities of the ~ m e r i c a n Chemical Society coupled with my college teaching activities has enabled me to maintain a close and constant contact with the college chemistry programs. Many students look to me for assistance in the selection of a colleee as well as a maior field. Approximately 100% of my studenggo on to college work, and manv of these maior in chemistrv. " . chemical eneineerine. -. phapmacy, physics, &d the medicinal sciences. To $ate, as far as I know 43 former students have earned doctorates. mostlv in chemistry. I cater to the disciolined student who is interested in hard and challenging woik. I have little patience with the lazy student, half-heartedly and aimlessly going through the motions of a public school education. Therefore, I have been involved, for the most part, with advanced classes and studies. Of course, I draw a few loafers in my classes placed there by the computer. Some of these I am able to convert to serious study through a relevancy approach to chemistry while the rest transfer to regular classes. I am not trying to make chemists of all of my students. Instead, my maior interest is to provide each student with a good, hard lodk at introductorichemistry, its methods, and its opportunities, while providing them with a good functional background for college-study. I prefer the lahoratory approach to the teaching of Chemistrv I-Advanced and Chemistrv II-AP. The latter course grekly appeals to the science-oriented study. This course must, in all fairness to the student, he a rigorous treatise in order for a student to properly evaluate his chances of a top performance in chemistry a t the college level, either as a chemistry major, or in the fields of chemical engineering, textiles, pharmacy, etc. Mnn is innately curious and his rontinuous use of experimentation has rwulted in the ev~lutionof modern chemi~nl concrpk 'This hns resulted in tht: so-rallcd mudtm way of life. I lirmly helie\.e that high school chttmistry courses must bring into focus a thouehtful nnalvsis of the evolution of chemirnl theories and the; practicalapplication in the student's life and the world around himiher. Volume 58, Number 10, October 1979 / 671
