view from my classroom
--, FRANK CARDULLA Niles Township High School 9800 Lawler Skokie. IL60077
Precolumbian Chemistry A Descriptive Chemistry and History of Technology from Natural Resources: Metallurgy, Pottery, Pigments, Dyes, Agriculture, and Medicine Janet Bond ~ o b i n s o n ' Decorah High School, Decorah, IA 52101 Several years ago, following a cumculum section on chemical histom. one of mv Iowa chemistrv students asked me. "WasnY a&hing goiAg on over here?'' Generally, the hegin: nings of chemical history have been focused on the metallurgy a n d crafts of t h e ancient Egyptians and Mesopotamians. a n area of the world about which American students are not very familiar. That student's question and a n opportunity to visit t h e Yucatan peninsula on a study tour prompted me to write a "Precolumbian Chemistry" curriculum for my high school chemistry students. The group of curricular materials I prepared has a two-fold purpose: 1. to develop the descriptive chemistry of elements and eompounds within a cultural context so that it is mare mean-
ineful to students. and " 2. to show haw technology develops by trial and error from
the natural resources of a particular region, in this case that of Mexico. Central America. and northwestern South America. T h e a r e a of Mexico, Central America, and northern South America was chosen a s the cultural context because i t is closer to home for American students and is the area in which technological innovations of the Aztec, Incan, and Mayan civilizations developed. Many of these innovations have been studied in recent years. Precolumbian Chemistry Curriculum Format The curricular materials for the unit on Precolumbian Chemistry include: 1. A booklet of information to explain and illustrate how
the technology of ancient Americans and their production of agriculture, medicine, metallurgy, and pigments can he
related to principles of geochemistry and biochemistry. See the contents of the booklet in the tahle. 2. A group of 13 labs andlor demonstrations. They are designed both to assist students in improving observation skills and to teach them about the characteristics of metals, crystal structure af solids, colors of various compounds, and methods of smelting metals from ares, extracting pigments from plants, and dyeing textiles. This paper was presented at the January 1993 SACNAS (Society for Advancement of Chicanos and Native Americans in Science) Annual Conference in Albuquerque, NM, and presented at the July 1993 NSTA International Conference in Oaxtepec, Mexico, to Mexican and American teachers. Will be presented at ChemEd 95 in Norfolk,VA in August 1995. 'Currently on leave for a fellowship at Wright Center for Innovation in Science Education, Tufts University, 4 Colby Street, Medford. MA 02155.
416
Journal of Chemical Education
Contents of Precolumbian Chemistry Preface and Obiectives for this Unit Preco "moan CLtxes Chapter 1 nModeAmerca Geochemistry: Minerals to Metallurgy Chapter 2 The Geochemistry of Pottery, Chapter 3 Painting, and Sculpture Biochemistry: Food and Fashion Chapter 4 Biochemistry and the Roots Chapter 5 of Medicine Labs to Accompany Chapter 6 Precolumbian Chemistry References Appendices for the Teacher 3. Study guides for Chapters 2-5. These guides help stu-
dents extract the chemical concepts from the cultural eontext, thus allowing them to focus their attention on these concepts. 4. Essay quizzes covering metallurgy, the lab work in Chapters 3-4, and medicines, and an objective test covering the entire unit. Uses for This Curriculum 1. It was designed far high school ehemistry at the juniorsenior level: either the first chemistry or an advanced chemistry class. 2. It could be used for a college-level archeological chemistry course for majors or nan-majors, especially during a month long class. It would integrate their previously learned chemistry-biology-arth science into a cultural and historical context.
Rationale for this Particular Unit in High School Chemistry It is advantageous to teach the early roots of science because it will seem less austere and academic to the student than modern science. Early science was very "concrete" in an educational sense, because ancient Americans experimented with the matter found in their environment. From these natural resources manipulated hv a trial-and-error (emuincall approach, early ~ i e r i c a n sdiscovered and created h a y vessels, metallic objects, dyes and pigments, and medicines to make their lives more productive, satisfying, and safe. These technolo~caldevelopments from elements, compounds, and mixtun,.%found n;itur;illy cr~mplisrtne eisenrinl nature of mrlg chclni:tly 111ci.;t!na!, this unit t t ~ ~ h tthe r s "descnpti\,e chem~stry"that has been ahsent in mo;t curriculun~rinw thv IYGO'$, but i n a cultural context that integrates it with the earth science and biology that students have studied recently
In addition, this topic of drugs and medicine provides an opportunity to discuss the drug education suggested a t every grade level in Iowa. Motivation Scheme
Rather than a rigorous memorization of facts, the hope is that students will get involved with the early Americans' struggles and triumphs to improve their existence. Studying the chemistry of ancient Americans can help students understand many important aspects of science: k e e n observation, obtaining useful materials upon which to experiment, trying new ideas, the skillful manipulation of materials, use of combustion, and perseverance. These are the very activities of early civilizations'science a s well a s modern. The only difference, and the reason for the flourishing of scientific developments in the last couple centuries, is the use of a "scientific method." Following this unit the students are in a position to appreciate the benefits of a scientific method. Fining the Unit into Existing High School Chemistry Curriculum
Basically this is a unit of descriptive chemistry discussing properties of elements and compounds used by the ancient Americans from their environments. In addition, i t tells the early history of chemical technology a s ideas and skills developed. Beginning the school year with chemical safety and combustion, this unit replaces standard introductory topics i n high school texts: divisions of chemistry, history of chemistry, benefits of the scientific method, substances, mixtures, chemical and physical properties of substances such as density and reactivity, separation of mixtures by substance properties, elemental composition of the earth, quantitative measurements, and adds much more lab work than had been done a t this point i n the past. Following this unit there will be an addition of chemical history up through alchemy to Boyle, Priestly, Lavoisier, and Dalton and then to atomic theory. The unit on Precolumbian Chemistry takes three to five weeks dependingon how much time i s spent on laboratory investigations. Most class time is spent i n lab work while the reading and study guides generally are meant to be done a s homework. Occasionally study guides are done as cooperative group work
i n class. Class members are often called upon to discuss and clarify what has been learned in labwork. Labs to Accompany Precolumbian Chemistry The purpose of labwork in chemistry is two-fold: 1. to help students experience the concepts discussed in the
text, and 2. ta gain experimental skills and reasoning.
While several of the labs are original, most are versions of fairly standard labs-but within a context of thinking about what early peoples could have learned about matter. The purDose of these labs is to pet into the trial-and-emr Drocess bv khich early science was done. Ancient peoples ex&rimentei on matter "close to home." and some of the followine labs will attempt to mimic the procedures they did. The & p o s e of these labs is for students to gain experimental skills and strengthen their reasoning ski& They also allow students to observe manv different properties of substances and lead . . them to see how thew properties cm Ire exploited by the PX~enmenter.The srnelt~ngdernonstrnt~onofcuvnc oxlde illustrates to students how an ore-containingrockcan be crushed to a powder, heated with charcoal, and subsequently reacted in a redox reaction to produce pure metal. Students fmd this production of pure metal amazingjust as the ancient artisans must have! Some of the other labs, such as those using the microscope and chromatography, will enable studknts to use more modern equipment and techniques. The students seem interested pa&cularly i n separations of mixtures as a puzzle and how chromatography separates similar molecules. In preparing for chromatography, students learn how to pull glass capillaries from standard glass tubes, an activity they appear to enjoy especially. Although the Precolumbians did not work with glass, i t was very common i n the Middle East. At this ooint students can be shown how modern separation and identification technioues can have vervuseful and ~ r a c t i c aal . ~.~ l i c a t i o nFor s. example, a description of how a clinical lab can identify and auantifv the amount of alcohol in a driver's blood is a topic rh:lt nt,\.wcwi.ivd to hold their int(!reit and attmtinn. Studcnt surveys mdwate that mterest is helnhiened when the relevance of a technique in the real worldcan be shown andlor when students are able to manipulate . physically a . material such as glass. The labs a r e shown i n sequence of investigation i n "Precolumbian Chemistry."
Rbout the Ruthor Janet Bond Robinson has a BS degree in medical technology from Texas Lutheran College in Seguin, TX, where her major field was chemistry. She has been teaching chemistry and physics at Decorah High School in Decorah, Iowa for the past six years, and several years prior to that she taught chemistry labs at Luther College in Decorah. While earning her B.S. degree, Ms Robinson completed a year's internship at the University of Texas Medical Branch in Galveston and was subsequently employed in clinical chemistry at Holy Cross Hospital in Salt Lake City, UT, the National Health Labs in Denver, Co, and Seton Medical Center in Austin. TX. Raising her own children sparked her interest in the educational process, eventually resulting in her earning a teaching certificate. Her MAfrom the University of Texas concentrated in chemical education and culminated in the report, "Modem Chemistry for the Price of a Tuba. M s Robinson's professional interests include understanding how students learn, promoting bener science understanding by both male and female students, and writing chemistry cunicula. Concerned wth the transformation of public education,she is keenly interested in creating and maintaining condhons that are conducive to high teacher effectiveness and bener student learning. She currently serves as president of the Decorah Education Association, and is an active member of the National Science Teachers Association, the Tristate Chemistry Teachers Alliance, and the Phi Delta Kappa Educational Fraternity In 1989 Ms. Robinson was awarded an ACS minigrant to develop an environmental curriculum entitled, "Water Pollution by Agricultural Chemicals. In 1992, assisted by an Eisenhower Minigrant, she developed chemical lab activities for 4th and 5th graders. These were then prepared and field tested by high school students who had completed a year of chemistry. She was chosen as a participant in both the 1993 AAAS Forum on School Science in Washington, D.C., and the 1st Gordon Conference on Science Education in 1992. Volume 72 Number 5 May 1995
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Lab Experiments Flame Tests Crystals under the Microscope Metal Reactivity by Single Replacement Reactions
~ & Identification: k ChemiciiTests ' Separation of a Mixture Using Mordants with Dyestuffs Marbelizingis Art and Chemistry Chromatography to Separate Molecules in Food Colors Plant Extraction for Pigments Chromatography to Separate Plant Pigments Cautions When conducting these labs, i t is important that all recommended safety precautions be observed. Students should at all times wear safety goggles that carry the 287 stamp. Several of the labs utilize volatile solvents. These solvents should be used only in a ventilated fame hood, never in the open classroom. The smelting demonstration always should he doneunder a fume hood and should be done only as a demonstration.
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Discussion The curriculum originally was written in the summer of 1991 and field-tested among my four classes of chemistry in September of the same year. The following summer the booklet and the studv mides were revised extensively and the revision field-tested-with my four new chemistry classes in September 1992. This led to revision of several of the laboratory activities. Copies were sent to reviewers2 who read and assessed the accuracy of the scientific content. The chemistry teacher in a neiehborine " " communitv? field-tested this eurriculum with a second-year chemistry class in the fall of 1992. Student feedback indicated that the lab activities especially were enjoyable, and the material contained in the booklet was judged to be new to them. The reading level appeared to be challenging for the average high school student, but they indicated that the studv mides omved verv. helpful . in dckingout essential chemical il;forma
