Chemical Education Today
Reports from Other Journals
The Science Teacher: Spring 2004 by Steve Long
This review covers chemistry articles that were published in the September through December 2003 issues of The Science Teacher (TST). Topics of possible interest to JCE readers in TST are drawn from the September and October issues; these include buoyancy, density, molar volumes of gases, absorption spectra, and the electromagnetic spectrum. The articles focus upon inquiry learning, lab activities, and links between chemistry and other sciences. (While the November and December issues of TST contain many interesting articles, they did not contain any with a chemistry focus.) “Fun with Buoyancy” describes a lab activity successfully used with middle school through high school students. The authors claim that “the topics of volume, measurement, density, and buoyancy can be easily combined into one lesson.” High school students are more likely to develop the understanding of buoyancy through this activity. Students fill with sand containers of various shapes and sizes until they barely float in an aquarium filled with water. Then, students mathematically solve for the buoyancy and density of the objects and graph their results. A more complete discussion of buoyancy measurements by Bernard Miller appeared in this Journal (1). Titled “Buoyancy Measurements for Teaching and Research”, Miller discussed details that may be useful for more advanced high school students or as background material for teachers. Topics included a review of the buoyancy principle, measuring buoyancy, the wetting force, and the application of the buoyancy force measurement. A favorite density and buoyancy activity of many students, Cartesian divers, is provided as a JCE Classroom Activity, “Sink or Swim: The Cartesian Diver” with both instructor and student information ready for duplication (2). On a similar topic, “Density on Dry Land” seeks to identify, understand, and rectify student misconceptions related to density. The authors believe that “some of these nonscientific ideas can be traced to experiences with buoyancy in water.” The authors describe some common student misunderstandings about density and some of their activities that are designed to allow students to clarify their knowledge of density. Using only solid materials in the activities removes the probability of student misconceptions involving density and water buoyancy. Numerous articles have been printed in this Journal concerning the fundamental concept of density. A recent article is “Beyond Density: An Inquiry-Based Activity Involving Students Searching for Relationships” (3). A short and interesting idea shared by Harvey Blanck, “Mass and Density–A Surprising Classroom Demonstration”, suggests that “the hand measures or compares pressure rather than force” when a person “hefts” an object in the hand (4). An excellent article by Richardson and Teggins explains an introductory lab experiment for beginning (college) chemistry students that could also be appropriate for high school students (5). In this experiment students measure the masses and volumes of successive additions of an unknown liquid 462
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into a graduated cylinder. Students then measure the masses and volumes of successive additions of a solid into a waterfilled graduated cylinder. Finally, they graph and analyze the slope of the line to determine the density. These activities could be adapted to use the graphing calculators that many students have. Jesse Bernstein provides a “Recipe for Inquiry” as he explains how to modify a traditional molar volume of a gas experiment for an inquiry-based lab approach. Rather than use the traditional laboratory experience as essentially a process to practice calculations, Bernstein divides the class into groups and assigns each group a different volume of gas to collect. Students are shown the experimental setup and essential techniques before they perform their calculations and begin collecting the gas. A rubric for assessing student success and a discussion of assessment is included in the article. Bernstein states that he has modified many experiments to incorporate an inquiry approach. He says, “Inquiry-based laboratory experiments appear to motivate students to work with more care and better precision in the laboratory and ask more creative questions.” A search of the JCE archives indicates four articles with demonstrations or experiments on the concept of molar volumes of gases (6–9). Following Bernstein’s directions, readers could possibly modify these procedures for an inquiry-based approach. A biochemical lab activity using a spectrophotometer to measure protease activity in flavored gelatin is the focus of “Supermarket Proteases”. Meat tenderizer, pineapple juice, and contact lens cleaner proteases are used for the hydrolysis of flavored gelatin, which releases pigment that can be measured with a spectrophotometer. Instructions for conducting the experiment and graphs of sample data are included in the article. The experiment also contains an extension for monitoring the effect of pH on the proteases used for gelatin hydrolysis. In addition, the authors discuss appropriate assessment of the activity. This experiment may be an interesting and real-world extension to the use of spectrophotometers as traditionally taught in chemistry classrooms. Another experiment using a spectrophotometer to measure enzyme activity was described in this Journal by Hurlbut and coworkers (10). A chemistry and astronomy connection is made in “The Electromagnetic Spectrum”. The analysis of infrared, visible, and ultraviolet light from the heavens allows astronomers to identify the elements comprising distant celestial bodies. “Chemical Detective Activity” is an inquiry-based chemistry project included within this article. The activity guides students through a discovery of the spectra of various light sources and draws the analogy that the emission spectra of elements are as unique and identifying as are the fingerprints of humans. Two ready-to-use activity sheets and a discussion of assessment accompany the activity. The connection between astronomy and chemistry makes this article useful to both
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Chemical Education Today
teachers and students. Three articles from JCE complement this TST activity. “A Visible Spectrometer” details how to use an overhead projector to demonstrate both the emission and the absorption spectra of colored light (11). Marie Sherman describes how she uses a Spectronic 20 to demonstrate the visible spectrum of white light to her high school students (12). “The Electromagnetic Spectrum in Chemistry” provides background for teachers (or students) who want an understandable review of the electromagnetic spectrum (13). Literature Cited
TST Featured Articles
1. Miller, B. J. Chem. Educ. 1989, 66, 267–270. 2. Pinkerton, K. J. Chem. Educ. 2001, 78, 200A–200B. 3. DeMeo, S. J. Chem. Educ. 2001, 78, 201–203.
4. Blanck, H. J. Chem. Educ. 1977, 54, 628. 5. Richardson, W.; Teggins, J. J. Chem. Educ. 1988, 65, 1013– 1014. 6. Koster, D.; Trimble, R. J. Chem. Educ. 1994, 71, 528. 7. Hughes, E., Jr. J. Chem. Educ. 1992, 69, 763. 8. Freeman, R.; Gorin, G. J. Chem. Educ. 1988, 65, 1044. 9. Zaborowski, L. J. Chem. Educ. 1972, 49, 361. 10. Hurlbut, J.; Kavianian, G.; Lee, S.; Nutall, K.; Gentry, S.; Hassman, T. J. Chem. Educ. 1977, 54, 442. 11. Martin, J. J. Chem. Educ. 1990, 67, 1061–1062. 12. Sherman, M. J. Chem. Educ. 1987, 64, 627–628. 13. Davies, M. J. Chem. Educ. 1954, 31, 89–91.
Steve Long teaches at Rogers High School, Rogers, AR 72756;
[email protected].
Cuicchi, Paul M.; Winter, Joshua B.; Hamil, Burnette. Fun with Buoyancy. TST 2003, 70 (6), 42–45. Libarkin, Julie C.; Crockett, Cynthia D.; Sadler, Philip M. Density on Dry Land. TST 2003, 70 (6), 46–50. Bernstein, Jesse. A Recipe for Inquiry. TST 2003, 70 (6), 60–63. Hagar, William G.; Bullerwell, Lornie D. Supermarket Proteases. TST 2003, 70 (7), 26–30. Smith, Denise; Eisenhamer, Bonnie; DeVore, Edna; Bianchi, Luciana. The Electromagnetic Spectrum. TST 2003, 70 (7), 47–51.
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