Chemistry Everyday for Everyone
Teaching Concepts in Beginning Chemistry with Simple Exploratory Experiments Lee D. Hansen1, Judy L. Garner, Byron J. Wilson, Coran L. Cluff, and Francis R. Nordmeyer Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602
Most students in beginning chemistry courses are neither chemistry nor physical science majors, but need and want to learn to use fundamental theories, models, and laws to gain an understanding of a wide range of phenomena. The typical beginning chemistry course consists of lectures, demonstrations, homework problems, and perhaps some laboratory. However, Tobias (1) has shown that most students are not happy with this quantitative, problem-solving approach to chemistry. Not only are students daunted by the inherent difficulty of the course work, but they also feel the learning experience is unfriendly and unrelated to their real interests. We have found that an “exploratory” (an open laboratory with guided discovery experiences) significantly improves student ratings of beginning chemistry courses and is an effective way to increase students’ understanding of chemistry. One student evaluated the exploratory with the proverb, “What I hear, I forget. What I see, I remember. What I do, I understand.” The typical laboratory experience in beginning highschool and college chemistry teaches techniques and measurement skills needed by students, but is ineffective at teaching concepts. The conceptual component is usually included as a part of the quantitative data analysis, and the evaluation is almost always based on the accuracy of results, not on the students’ understanding of concepts. Also, quantitative laboratory exercises tend to be tedious and frustrating for students. Lecture demonstrations can be fun to watch, but the lecturer is always there to explain what is happening and students are only passively involved. Also, demonstrations subtly, but forcefully, teach that only those who are already skilled can do chemistry. The exploratory is intended not to replace demonstrations or laboratory exercises currently included in chemistry curricula (hence the change in name to “exploratory”), but to fill in their deficiencies. The Exploratory Lab The exploratory lab consists of a series of hands-on, qualitative activities that are safe, simple, and inexpen-
sive, use readily available supplies, and illustrate a concept concurrently being studied in the course. An unscheduled laboratory with minimal supervision saves space and money. Experiments take 15 to 30 minutes, and students are strongly urged to work in groups of 3 to 5 so they benefit from interactive discussions. To promote open discussion, the exploratory is graded on attendance only. Table 1 lists 30 exploratory experiments that were tested on several thousand college chemistry students. This set of experiments has recently been published (2). Since there is minimal supervision, safety and theft prevention are major concerns. Equipment is inexpensive or locked down and chemicals are used in micro amounts or are common household supplies.
Examples of Exploratory Experiments Students learn about gas density and diffusion by observing the behavior of three labeled balloons during the 24 hours after these are filled with He, air, and SF6. The “dipping bird” found in novelty shops helps students understand evaporation and the vapor pressure of liquids. “The case of the unlabeled bottles” teaches students about chemical properties as they use a multiwell plate and a few drops of each reagent from a collection of knowns and unknowns to observe chemical reactions and identify the unknowns. Students see various oxidation states of manganese resulting from mixing solutions of KMnO4 and NaHSO3. They learn about temperature, heat capacity, and heats of reaction by burning a nut, a potato chip, and a dried bread crouton under a soda can halffilled with water. Implementation of the Exploratory Students are provided a brief introduction to, instructions for, and questions on each experiment. These are designed both to pique student interest and to inform of the concept illustrated. Catchy titles are used to generate curiosity, but minimal detail is given so students do not know the expected result of the experiment. If necessary, more complete instructions are given on a chalk-
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Corresponding author. 801-378-2040; 801-378-5474 (FAX). Presented at the joint meeting of the Northwest and Rocky Mountain Regional ACS meeting, Park City, UT, June 14-17, 1995.
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Chemistry Everyday for Everyone
board or taped to the lab bench for the current experiment. Open-ended questions guide the students’ discovery of the concept or application. At BYU, the exploratory is open 10 hours per day, Monday through Friday, and part of Saturday. Students are expected to do one experiment per week, but are free to do the experiment any time during the week. Five percent of the course grade is based on attendance as implied by completed lab reports. Experiments are set up and taken down during the weekend by a part-time teaching assistant. Exploratory space requirements are minimal: about 6 feet of lab bench (or ordinary tables) and one experimental setup are adequate for every 250 students. Major equipment required to do all thirty of the published experiments is a balance (4 kg capacity with 10 mg resolution is optimum), a simple centrifuge, some gas regulators, and some volt–ohmmeters in the $20–70 range. Many experiments can be done with materials available from local hardware and grocery stores. Plastic wrap, aluminum foil, Beral pipets, 4-ounce dropper bottles, and plastic multiwell plates are used extensively. Safety is an extremely important consideration because of the unsupervised situation. Safety goggles (premarked and of an unusual color to avoid “borrowing”)
are provided at the entrance to the laboratory. A safety contract establishing rules of conduct in the laboratory is required of all students. Teaching assistants are available about 35 hours per week, but are not always physically present in the exploratory room. We have completed four years of testing the exploratory program, most recently with about 1200 first semester chemistry students and about 300 second semester students. Currently, lectures are taught by several professors in seven different sections. A total of 80 hours per week of student teaching assistant time is used to operate the exploratory, including grading. Most of the teaching assistants are undergraduate chemistry majors. The exploratory room is about 20 × 24 feet. It is furnished with one small laboratory bench and sink, one small hood of the kitchen-stove variety, a blackboard, a bulletin board, a box for receiving completed reports, and a miscellaneous assortment of tables and chairs. The supplies and equipment budget for the year is about $3000 to cover a total student load of about 2500 students per year. This amount has proved to be sufficient to maintain and operate the exploratory, purchase some new permanent equipment, and allow some development of new experiments and materials.
Table 1. Publisheda Exploratory Experiments Title
Description
Absolute Zero
Evaluating absolute zero from PVT relations
Atomic Spectra
Observing the line spectra of elements
Birds of a Feather
Observing the solubility of polar and nonpolar substances in water and oil
Buffers
Showing the action of acids and bases on buffered and unbuffered solutions
BYU Thermometer
Defining an arbitrary temperature scale and converting temperatures from one scale to another
Case of the Unlabeled Bottle
Identifying ions in solution by chemical properties
Cloud Chamber
Observing alpha particle tracks in a cloud chamber
Collapsing Can
Observing the effects of atmospheric pressure on a partially evacuated aluminum soft-drink can
Crystalline Solids
Observing the shapes, colors and cleavage planes of crystalline minerals
Dipping Bird
Explaining the action of the dipping bird by liquid vapor pressure
Electrolysis of Salt Solutions
Observing the products at the anode and cathode in solutions of KI, KCl, AgNO3, and CuSO4
Galvanic Lemon
Measuring the relative E°of Zn, Fe, Mg, Pb, and Sn
Gaseous Molecules
Measuring density and calculating molecular weight of monatomic and diatomic gases
Household Materials: Acids or Bases
Measuring pH with universal indicator paper
How Big Is a Mole
Measuring and observing the masses and volumes of 1 mole of several substances
How Low Can You Get?
Measuring the freezing point depression in sugar and salt solutions
Hungry Pyromaniac
Measuring the heats of combustion of various food items
Hydrogen-Oxygen Rockets
Observing the energy of reaction of various mixtures of H2 and O2
Kool-Aid Chromatography
Observing the separation of dyes with paper chromatography
Lead Balloon
Observing the effects of molar mass on the diffusion rates of various gases
M&Ms-Moles and Molecules
Demonstrating the concept of counting by weighing
Models of Molecules
Making and observing models of molecular shapes predicted by VSEPR theory
Oxidation States of Manganese
Producing and observing Mn2+, MnO2, MnO42–, and MnO4–
pH Indicators
Observing the colors of several indicators in solutions of pH 1 to 12
Precipitation Stoichiometry
Determining the formulas of several ionic salts
Reactions of Some Metal Ions
Observing the precipitation, complexation and amphoteric behavior of Mg2+, Al3+, and Cu2+
Temperature Effect on Solubility
Observing supersaturation and solubilities that increase and decrease with temperature
Testing for Proteins with the Biuret Test Determining the relative protein content of various foods Titration of a Strong Acid with a Performing an acid-base titration with an acid-base indicator Strong Base Water, a Compound or an Element? Observing the electrolytic decomposition of water
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Chemistry Everyday for Everyone
Results Student response to the exploratory has been very positive. Surveys designed to test student attitudes show a one-point difference on a five-point scale between sections of the same class with and without the exploratory. Within-section surveys show the same difference in attitude between students in the exploratory and those not included or not attending. Students like the exploratory and feel that they learn much that is valuable. Anecdotal evidence leads us to expect that exam scores will show improvement as the exploratory becomes more integrated into the program. As one visitor from another university exclaimed in amazement, “They’re actually talking about chemistry in there.” The exploratory is a place where students actually argue with each other about the application and meaning of principles and concepts of chemistry. Encouraging such exchange of ideas by having students work in small groups without grade competition is a very important part of the philosophy behind the exploratory. Anecdotal data also convince us that the observed changes are a real effect and not a “placebo” effect. Many of the professors teaching courses associated with the exploratory were cautious of or resistant to adding the program, but some of our most ardent supporters are now from this group. Allaying the fear that the exploratory was intended to displace traditional chemistry laboratory work was a major difficulty in introducing the program. We plan to continue to develop the exploratory by greatly expanding the repertoire of experiments available, and publishing them so they are widely available to the teaching community. Many more experiments are needed to meet the needs of students on various tracks. Students in the majors course have different abilities and needs than students in terminal, lower-level courses. Also, texts vary in content. Summary The exploratory is an incremental addition to existing curricula that does not require large capital expenditures for new equipment, but accomplishes the goal of making beginning chemistry more fun and relevant to students. The exploratory experience makes science more appealing to a broader audience. The critical thinking skills developed in this program empower students to think for themselves and to become more active learners. While the existing exploratory program is aimed at the beginning college chemistry student who is not a chem-
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istry major, the methodology is adaptable to other levels such as high schools and more rigorous chemistry courses. The exploratory concept is also adaptable to other sciences such as physics and biology. However, the program must be tailored to the audience. For example, the same experiments that work well with an introductory college chemistry class do not work with students who have previously had high school chemistry. The portability afforded by minimal equipment costs and readily available materials is also an important aspect of the exploratory. In our opinion, giving teachers new ideas that are simple and effective when implemented in the classroom is the best way in the long term to revolutionize the chemistry curriculum. Our experience in the pilot program suggests that this program can be readily adopted even by teachers who are not enthusiastic about changing the curriculum. We find that adding the exploratory to the curriculum actually reduces the teacher’s work load because students spend more time in unsupervised learning activities. Once students learn the process of “figuring things out” for themselves, they become much more independent. In summary, the exploratory evokes modes of learning that for the most part are not present in the current chemistry curriculum and pedagogy. It can be added to existing curricula with minimal cost and effort, to produce a measurable, positive effect on student attitudes about science. Acknowledgment The authors acknowledge the assistance of Justin T. Barratt, Stephen R. Boden, Michael A. Canady, Brenda Christensen, Angela R. Egbert, Gurvais C. Grigg, Bret D. Heileson, Steve Jensen, David C. Jones, Jeremy B. Nicoll, Jim Pace, Hilary Porter Parry, Michael W. Scheetz, and Teresa J. Warner in development and testing of the exploratory program. Literature Cited 1. Tobias, S. They’re Not Dumb, They’re Different; Research Corporation: Tucson, AZ, 1990. 2. Hansen, L. D.; Nordmeyer, F. R. Exploratory Experiments in Chemistry; KendallHunt: Dubuque, IA, 1994.
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