Chemical Education Today
Especially for High School Teachers
by J. Emory Howell
Making Connections vs Relevance: Chemistry and Biology For many years there has been a movement to make chemistry more relevant to learners, particularly in introductory chemistry courses. Sidebars describing chemical applications to real-world settings are sprinkled throughout textbooks. Consumer products are often used in place of reagent-grade chemicals, not only as a means of cost saving, but also in an attempt to make chemistry more relevant for the beginning learner. The Journal has published many articles dealing with the application of chemistry to other disciplines. As our understanding of the importance of constructivism in intellectual development has increased, the need to help students make connections between the knowledge they have constructed and their experiences in the classroom and laboratory has become more evident. The need is much deeper than simply recognizing familiar products or observing visible chemical changes. Relevance appears to be a helpful and perhaps necessary condition for learning, but it does not appear to be sufficient to ensure that connections are made between chemical concepts new to the learner and previously constructed knowledge. This month’s JCE Classroom Activity “Soup or Salad? Investigating the Action of Enzymes in Fruit on Gelatin” (p 624A) is an example of an experiment that requires the student to use biological concepts to carry out a chemical investigation. The action of proteases from fresh or frozen pineapple and meat tenderizers on the proteins that provide the structure of gelatin is compared with the action of fruit that has been canned or heated in a microwave. Like other JCE Classroom Activities, references, additional information, and related activities are cited. The activity can be used in the classroom or assigned as a take-home activity. JCE Classroom Activity #15, “Liver and Onions: DNA Extraction from Animal and Plant Tissues” (p 400A, March 1999) also integrates chemical and biological concepts. The JCE Software videotape HIV-1 Protease: An Enzyme at Work is another useful resource. It can be used in any classroom where kinetics, catalysis, proteins, or enzymes are discussed. Information about JCE Software products can be found in recent issues of the Journal or by accessing JCE Online (http://jchemed.chem.wisc.edu). Because most high school students complete at least one year of biology before enrolling in chemistry, developing the connections between biology and chemistry can be especially productive. Connections between chemistry and biology often seem to be more real to students than do many of the phenomena we cite as applications. For example, students often are not able to make the connection between the excitation of electrons to produce electromagnetic radiation and anything that is personally relevant. The light given off by sodium or mercury vapor lights provides a common example of relating atomic emission to a useful process, but many students do not seem to find that particularly interesting. The need to make a connection between biology and chemistry becomes especially meaningful to students when the chemical change occurs within the human body. As an example, the interaction of emitted electromagnetic radiation with human cells to cause well-tanned skin seems more relevant to a greater number of
Secondary School Feature Articles t An Elementary Outreach Program—Have Demo Will Travel, by James Swim, p 625 t Pressure and Stoichiometry, by Charles E. Roser and Catherine L. McCluskey, p 638
students than the color of lights in a parking lot. This issue contains an article that describes a useful application of light to kill cancer cells through use of photosensitizers (p 592). The process of photodynamic therapy (PDT) provides another example that could help students make a connection between the emission of electromagnetic radiation and the challenge of killing cancer cells without harming healthy cells. Certainly this example is not a magic antidote to “why do we have to learn this stuff” and it doesn’t directly relate atomic spectra to quantum theory. It does, however, deal with energy–matter interactions in a topic that is more relevant to students’ daily lives. And in turn, the concept of electromagnetic radiation interacting with matter may be more important for most students to understand than is the quantum mechanical explanation of electronic configuration. This issue contains several other articles from which useful examples connecting chemistry and biology can be drawn. Most of these are not indicated in the table of contents with the high school mark (t) because they are written primarily for college biochemistry faculty members. However, many high school teachers who read this column have strong backgrounds in biology and can find useful information in some of these articles. A keyword search for “enzyme” using the online index (http://jchemed.chem.wisc.edu/Journal/Search/) yielded 75 articles published between January 1990 and the present, illustrating that a great deal about this topic alone has been published in this Journal. Other “biochemical” keywords that can be used to search the index include amino acids, biotechnology, hormones, lipids, metabolism, nucleic acids/DNA/ RNA, and proteins/peptides. Other biological connections are evidenced through keywords such as drugs/pharmaceuticals, food science, medicinal chemistry, nutrition, and vitamins. Chemical Mysteries Revealed Online Ron DeLorenzo, editor of the Applications and Analogies feature, recently sent an email message describing a resource of interest to high school teachers. The Greenwich Science Education Center, Greenwich, Connecticut, is now displaying on their Web site (http://www.educationcenter.org) about 100 of DeLorenzo’s interesting mystery articles. Anaheim and Boston To those readers who stopped by the JCE booth at the ACS National Meeting in Anaheim or at the NSTA convention Boston we wish to say thank you. Also, thank you to those with whom we spoke at the outstanding High School Program at Anaheim. Watch the June issue for more about these two outstanding conventions.
JChemEd.chem.wisc.edu • Vol. 76 No. 5 May 1999 • Journal of Chemical Education
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