I Remember a Single Red Rose Helen M. Stone 2815 Lenoir Drive, Greensboro, NC 27408
Using only a ruler, how many measurements must be made to determine the volume of a matchbox? Each year I get astonishing answers to this pretest item-"28" is the most intriguing so far. I wonder what went through the student's mind. Was he guessing the number of matches and assuming this number equal to volume? For another question "How many feet in a yard?", "39.37" is a common answer. The implicationsinherent in this fact may be significant for those of us who like to believe that the numbers our students toss about mean something to them. There are the cold statistics of teaching in an inner-city hieh school in Greensboro, North Carolina-an average SAT score of 772, a score 82 points lower than our city's average, 64 points lower than the state, and 131 points lower than the national average-hints a t the challenges awaiting the ambitious teacher. Even in my Advanced Placement Chemistry class. the averape mathematics SAT score is 586 (a record highj, the average SAT verbal is 469. But a teacher does not teach averaees. A teacher dailv confronts the challenges of indiuidua1s:many who come from project homes headed by a single parent or grandparent, from homes where teenage girls often have one or two babies before leaving high school, from parents whose own education stopped a t the eighth grade, from homes with neither books nor newspapers. From homes with TV's on. At least half of my students work after school, perhaps as much as 30 or 40 hours a week, sometimes having to close at 200 a.m. T o go to work, one must have a car. To feed a car, one must work. When they go home, the T V is on. The score? TV-1, Homework-4.
With some students, the challenge of teaching chemistry may appear overwhelming, perhaps even hopeless. 1 recall girl enrolled in chemistry who could not solve algebraic questions as simnle as " 2 x = 10: x = ?". and could onlv identifv 20% of the &mbols of the klements after two weeks of instruction. Later in the year she made an appointment for after-school help. Optimistically I asked "What can I help you with?" She replied "I need help with everything!" "Everything" is a difficult place to begin, so I asked her to select one thing a t a time. She returned the next afternoon. "I don't understand how you figured out how much 3 moles of potassium chlorate weigb."Breathing deeply and choosing what I considered an apt analogy, I told her, "Close your eyes and imagine you are sitting a t your kitchen table. On the table are two bags of sugar, each weighing five pounds. How many pounds of suear do vou have?" Confidentlv she resnonded. "Twentvmy shock I said, "Lkt me teli i t to you again.';I five." did-slowlv. With a ~ u z z l e dlook she answered. "Twentvfive. You multiply, don't you?" For such astudent the road to understanding chemistrv stretches long. ... indeed. As you can see, teachinichemimy at my school is a challenge! In March I am still reminding students to"divide by dee-downstairs number called dee denominator!" By ~ ~ r i l all are quite familiar with6.02 X 1023,but, unfortunately, too many consider that to be the number of liters in a mole or grams in an atom! You may well ask "How do you teach these students?" or even "Why do you try?" Let me answer the second question first.
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About the Author Helen Stone has been a public schwl teacher for the past 21 years, the last 20 at Ben L. Smlth High School. Greensbwo. NC. A holder of both a BA and an MEd degree from the University of Norm Csrollna-Greensboro, Stone has continually updated her academic background in summer programs that include Duke, the 1982 Dreyfus Workshop at Rinceton, and Hope College. An active professional. Stone has conducted numerous APP Chemistry workshops, served as an APP Chemistry Reader, conducted a 1983 Dreyius Regional Workshop, and made numerous presentations at NSTA, NCSTA, BCCE. ChemEd, and regional NSTA and ACS conferences. An active member of the ACS-NSTA ADV Examinations Committee since 1980, Stone chaired the committee which prepared the 1986 examinallon and currently chairs the 1992 examination committee. An active ACS member, she has served as Treasurer of the Central NC Section In 1989. Secretary In 1990, and wlll bechair of the Section In 1992.For several years she has been a Trustee for the Nonh Carolina Schwl of Sclence and Mathematics. Stone's contributionsto sclence teachino have been reroaniredbv numerousawwds. includlna ma f~rrtGovernor s/Busonessmen s Stale Award tor Sclence Teacntng on 1983. me ACS Sofflneastern Reg onal Awam in 1984, an0 oolh a Pres dent al Award and a Regma Cata yot Award n
494
Journal of Chemical Education
Why I Teach
I grew up in a paper miU town and lived in a four-room house from the time I was 5 years old until I was 18. A family trapped by the Depression, we had no hot running water, in fact, all facilities were outside the first year or two. To this day I cherish soaking in a tub of hot water! Not only my mother, but also her parents, who lived with us much of the time, were collegegraduates who fostered my love of reading. I suppose that learning firsthand how to overcome poverty through education made me yearn to show students the way. Keep in mind that there was no TV when I grew up! The "majority" of students at Ben L. Smith High School are "minority" students from very low socioeconomicbackgrounds. In addition, Smith High School is the designated English-Second-Language school serving all four of our inner city high schools. These foreign students, though often disadvantaged economically, are definitely advantaged when it comes to family support of education. Homework comes first, TV last. I continue to be amazed that a student from southeast Asia with little or no command of the English language can, in one year, surpass the achievement of many native American students. How I Teach
How do I teach these students? There's no one secret, but it takes a great deal of energy, patience, creativity, and a virtually inexhaustible reservoir of belief and hope that they can learn. To quote an old phrase, "On some days there just isn't enough of me to go around." However, most do learn. Even "twenty-five-pounds-of-sugar" repeated chemistry the next year and passed. I have spent my teaching career trying to develop what I refer to as "Pictures in the Mind". As an example, I explain copper sulfate pentahydrate pictorially, using a circle for the anhydride surrounded hy five diamonds representing the five waters of hydration. My students heat this blue hydrate in a test tube, a method far superior to using a crucible, because students can see the color change and see the water at the mouth of the test tube. As a result, scorching is rare, results are good, usually 35 to 37%water. When students add a dropperful of water to the anhydride they are astonished by the heat, the steam, and the color change. I t is a joy to have them also understand the hydrate idea via the circles and diamonds. In the hydrate the diamonds are attached; in the anhydride they are floating away. The pictorialmethod helps with empirical formulas, say of copper iodide. If the formula is Cu12, there would he one diamond and two circles; if CuI, one of each. Other variants
are theoretically possible. Draw them. Now, assuming that one iodine atom has a mass twice that of copper, it is easy to see that the first formula has a Cu:I mass ratio of 1:4, whereas the second has a mass ratio of 1:2. If the student is told that only Cu(1) and Cu(I1) exist, an oversimplification,then ask him or her how to explain an experimental ratio of 2:3 using pictures. The astute student will see that, if you take one unit of 1diamond12 circles and one unit of 1diamond11 circle, a 50:50 mixture of the two yields an apparent formula of CU& with a mass ratio of 1:3. Of course the "twenty-fivepounds-of-sugar" student is unlikely to see this, certainly not clearly. Real teaching is not one endless string of victories. Sketches also explain the concept of the lab itself. Picture I : Draw a coaper stria consistine of six circles. and reactine with one pairof iodihe diamonis. Picture 2:~opperstrip with two attached iodine atoms clinging to the copper atoms as a film of copper iodide which washes off. Picture 3: The shortened strip now containing only four atoms of unreacted copper. AU students see how three massings allow them to calculate the masses of iodine and copper reacted. Speaking of seeing, how do I k&a when they see it? Watch their eyes. Read their body language. Do not, I repeat, do not teach to the ceiling as did one professor I had! One technique I use is to ask questions that require a uisible response from each student. For exam~le.ask "How manv ele&ons are there in an atom of helium? d n your mark. Get set. Go!'' Hopefullv, each student will be holdine UD two fingers, not four, when I give the signal. Or ask'"& one proceeds down a column of the periodic table, metallic character.. . on your mark, get set, go!" Hopefully, all thumbs point up for "increase". This technique is a powerful tool for assessing student grasp of concepts, even for questions that cannot be answered "increase", "decrease", "left", "right", or a numher that is less than 10. For example, suppose I want to ask them the mass of 1mol of carbon. Rather than having them wave toes with fingers, give them numbered choices: (1) 6 g, (2) 12 g, (3) 24 g. Now cue them "On your mark.. ." to signal you their answer. On occasion their fingers visibly tell you they do not understand, thus allowing you to re-explain before the test. Have you ever noticed that medical doctors seem to have no concept of what good teaching requires physically? When I go to them with this foot, or that toe, or this knee hurting, they all say "Sit down while you're teaching." When I tell them that this is impossible, they look at me as if I am deranged! How can anyone sit down to teach? Atoms have to
About the Editor Frank Cardulla is a 27year veteran of public school teaching. Me last 26 at Niles
NWth High Schwi. Skokie. L. His BS and MS degrees were both received from the Universityof iiiinois. Further education has included 60 postgraduate hours as well as Several mini-courses. Cardulla has bugM regular, honors. APP, and Heanh Science chemisby as well as physics and acourae in science fwspeciai education students. in addition, he recently began teaching prospective science teachers at Nonhwestern University. An active professional,he regularly gives presentationsatISTA. IACT. BCCE. ChemEd,and ACS Conferences, and has conducted AP Chemistry workshops for several years. He has servedssa chemistry Reader and Table Leader for 12 yearsandalso wasa member of Me APP Chemistry Test Development Committee. He has served lhe ACS-NSTA Examinations Institute since 1978, as a wmminee member on both subcommittees I and 11, the Chair of the 1980 and 1982 ADV commiltees, Vice-chairman of the High Schwi testing program, a member of lhe Executive Advisory Comminee, and currently as a member of the Board of Trustees. in addition he is active in various SOCEDand DivChed commhtees and Task Forces. Cardulla'sstudents have consistently receivedawards in various chemistry competlions, and he has been recognized by receiving the 1981 Davidson Award for Chemisby Teaching, the 1982 Regional Catalyst Award. lhe 1987 National Cateiyst Award. and a 1968 Presidential Award f w Science Teaching.
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Volume 67
Number 6
June 1990
495
marry; molecules divorce. Mr. Zinc has t o knock the L out of HC1 and run away with Ms. Chloride. Not to mention atoms vihratina, rotating, translatina, or even all three modes of motionat the same time. Sit &wn? Not me. Maybe a t the end of this school sear when I retire, but until then I walk; I pace. The Payoff Is all this effort worthwhile? Well, yes and no. "No" when you compare your paycheck and working conditions with your daughter's, hut definitely "Yes!" when students come hack to sav vou made a difference in their lives. Thev mav reminisce adout the time you climbed up on the lab tible tb emphasize a trend on the periodic table. "Yes", again when your marginal student who struggled through AP chemistry and flunked (or chose not to take) the AP exam comes hack to visit four years later, thanks you for the course, and explains that taking AP allowed him t o complete a degree in pharmacy or engineering, a field that otherwise might have been out of reach. "Yes", when you attend a Duke Medical School graduation of 80 students, three of whom took your AP chemistry.
496
Journal of Chemical Education
Once I even got a single red rose. The Vietnamese student who hrought it lived in the project with his mother, his stepfather, and a number of stepbrothers and stepsisters. In fact it was so crowded and so noisy a t home that he made friends with a cah driver who drove him to the Hilton each evening where Tuan did his homework in the lobby. Tuan had an excellent grasp of mathematics hut extremely poor reading ability. One day he came by to get me to re-explain quantum numbers. When I asked him to turn to page 104 in his text. he refused. savine "I can't understand it." After I insisted; he opened his La;, began to read, and looked up in amazement. "That exolains it. doesn't it?!" Five vears later. Tuan brought me thk rose. He had just grad;ated from NCSU with a degree in engineering and was being interviewed for a job. Today he is a successful engineer in New York state. A victory such as this makes up for a lot of disannointments. Hy the time this article gets into print, I will probably he rocking in my chair and, perhaps even watching TV! I hope, for your sake, that all your studentscometo you moreable to do math, more willing to work, and that their parents turn off the TV! May you, too, one day receive a single red rose.
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