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Nonconventional Methods in Teaching Matter, Atoms, Molecules

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Nonconventional Methods in Teaching Matter, Atoms, Molecules How-to-Dolt NonconventionalMethods in Teaching MIatter, Atoms, Molecules & the Periodic Table for Nonmajor Students Abour A. Cherif Gerald E. Adams Charles E. Cannon Downloaded from http://online.ucpress.edu/abt/article-pdf/59/7/428/48245/4450349.pdf by guest on 26 September 2021 Instructional strategies that allow the visible particles called molecules, and abstract topics. Randy Moore (1994) integration of a variety of approaches that these molecules are made of even has urged teachers to ask their students such as hands-on activities, visualiza- smaller, invisible particles called atoms, to write, because writing is a powerful tion, writing, demonstrations, role and that atoms and subatomic particles tool, not only for putting down what is play, and guided inquiry are important are even further removed from direct already in their heads, but also for in bridging the gap between concrete experience. Likewise, it is not at all helping them to think, to discover, to and abstract understanding of scien- obvious how the list of elements that develop and to organize ideas, and to tific concepts and principles among we call the periodic table has any sense learn effectively. In 1986, "a survey students. The following are a few of the of organization at all. Students, espe- conducted by the National Assessment instructional strategies that we have cially those who prefer the sens- of Educational Progress (NAEP) of used in classes (from middle school ing mode of learning and perceiving 95,000 high school seniors showed that through introductory college courses) (Schroeder 1993), might have difficulty 76% of the students could not write an and have found to be useful in helping with these concepts, as a result of both imaginative essay, 80% could not write nonscience majors better understand the abstract nature of atomic theory a persuasive letter, and 62% wrote un- the nature of matter, atoms, molecules, and the extremely formal pattern rep- satisfactory prose" (Moore 1994, p. the periodic table, and other related resented by the periodic table'. There- 290). On the average, "high school stu- topics. fore, we attempt to find ways to help dents in the United States write fewer The understanding of matter and its our students understand these con- than 500 words per semester, while atomic properties is fundamental to the cepts, through methods like visualiza- students in England write about 1,000 study of most biological and physical tion of atomic and subatomic struc- words per week" (Moore 1994, p. 287). sciences in their present forms. For tures, writing stories or short essays example, in biology, a basic under- about atomic interactions that form standing of chemistry (the study of molecules, and by designing games Why Do We Believe There matter and the changes it undergoes) is and maps to navigate the periodic ta- Are Such Things fundamental to understanding how ble. We have collected, designed and as Atoms? cells, organisms, and ecosystems work. modified activities based on our expe- It is also important in understanding riences with our students who are spe- Classical experiments that led to the physiology, genetics, evolution, and cializing in areas of arts, media and development of given scientific con- the origin of life on the planet Earth. communication. cepts and principles we hold today, Therefore, students need to learn the The common thread among all the such as the principle that atoms are the atomic basis of matter and the periodic learning activities and ideas in this building blocks of matter, can be pow- properties of the elements, in order for paper is the integration of hands-on erful learning tools for the illustration them to succeed in understanding most activities and writing. This integration of the tenets of science. We have found scientific concepts presented in any sci- is the tool for interpretation, learning, these experiments, either in descriptive ence class. At the same time, it is not at expressing thoughts and ideas, and of form or as actual demonstrations in the all obvious that matter consists of in- demonstrating the understanding of classroom, to be powerful learning tools helping students conceptualize the invisible particles that we call at- 1 In a learning environment, effective in- oms. Following are a few of the class- Abour Cherif, Ph.D., teaches biology structors are always able to recognize stu- room demonstrations that are direct and science education; Gerald Ad- dents who prefer the "sensing" mode of analogies to the classical experiments ams, Ph.D., teaches geology and en- learning and perceiving (a practice-to-the- of Ernest Rutherford and his assistant, vironment; and Charles Cannon, ory route through highly structured instruc- Hans Geiger. These demonstrations led Ph.D., is the Chairperson of the De- tion), and those who prefer the "intuitive" partment of Science and Mathemat- mode (theory-to-practice approach through to Rutherford's model of an atom with ics, and teaches chemistry, all at Co- open-ended interaction), and can balance a tiny nucleus containing practically all lumbia College, Chicago, IL60605. their teaching styles accordingly (Schroeder the mass of the atom, with the rest of 1993). the atom's volume being empty space 428 THEAMERICAN BIOLOGY TEACHER, VOLUME 59, NO. 7, SEPTEMBER1997 through which subatomic particles can middleof thesphere is as smallas a peabut like planets, which orbit through easily pass. weighs severalmillion tons. A few flies mostly empty space around the sun.2 If matter is made of atoms, then flitting here and there throughoutthe there should be spaces between the sphererepresent the electrons. atoms through which smaller particles (Hill & Kolb 1995, pp. 61-62) Activity #2: Experimenting with might pass. If matter filled all the Aluminum Foil, a Geiger space, Rutherford reasoned, the parti- Activity #1: Using Analogy To cles would have no chance of getting Understand the Concept Counter, and a Low-Level through. With this idea in mind, Ruth- of Atoms Radioactive Source erford and Geiger (in 1908) bombarded One approach in helping your stu- Another possibility for simulating a thin metal foil with a beam of fast- dents through the concept of atoms this experiment is to use a Geiger moving particles (positively charged and the Rutherford and Geiger experi- counter and a low-level, alpha-emit- "alpha" particles from a radioactive ment involves a simple, yet effective, ting radioactive source, such as mona- source material). Specifically, they used a analogy. Ask your students to imagine zite, carnotite, fergusonite, thorite, zir- gold leaf beaten to a thinnessof only one taking a garden hose and spraying con, allanite, columbite-tantalite, or fifty-thousandth of an inch (which was water at a solid wall. Ask them how commercially prepared non-mineral still at least 2,000 atoms thick). In con- sources. (Note: many primary and sec- trast to their expectations, Rutherford much water would get through the ondary schools are and Geiger observed that almost all of wall and how much would bounce prohibited by state back, and discuss why this is the case. or local safety regulations from having the particles (approximately 95%) went Downloaded from http://online.ucpress.edu/abt/article-pdf/59/7/428/48245/4450349.pdf by guest on 26 September 2021 right through the seemingly solid foil Then ask your students what would such materials on the premises, so without being deflected at all, and amaz- happen if holes were cut in half the check on the regulations before trying ingly, only a few (approximately 5%) of surface of the wall, and then water was to obtain them.) Monazite and ferguso- the particles were sharply deflected; sprayed through the hose at that wall. nite are more radioactive, and should some even bounced back in the direction Ask how much water, in this case, be stored in a lead-lined container, or from which they came. would go through, and how much packed in lots of paper. They can be To provide a sound interpretation of would bounce back. Again, discuss obtained from scientific catalogs (such the gold-foil experiment, Rutherford why this is the case (hopefully, the as Sargent-Welch, VWR Scientific, or hypothesized that the solid material collective conclusion will be that half Science Kit & Boreal Laboratories) in was made of atoms, with most of the the water will go through and half will forms that are not harmful, or bor- "solid" part being concentrated in a bounce back). You might also give a rowed from the physics, chemistry or central region, the atom's nucleus. In second example, with a different frac- geology departments of local colleges addition, he proposed an arrangement tion of holes to solid wall (or perhaps a or universities. Aluminum foil may be of the positive and negative parts of the percentage of holes to solid wall), to used as the thin metal foil. atom with all the positively charged reinforce the direct relationship be- First, to demonstrate that the foil has matter and almost all of the mass also tween the percentage of holes and the no perceptible holes, take a piece of the concentrated in the nucleus. percentage of water getting through or foil and a six-inch length of plastic pipe bouncing back. (like the pipe you can get in a hardware Whenan alphaparticle, which is positively Now, ask your students what they the store for indoor plumbing, around one charged,approached positivelycharged think the wall would be like if they nucleus,it wasstrongly repelled and there- inch in diameter), and seal one end of sprayed water at it, and 95% went Since a the pipe with the foil. You may need to fore deflected. only few alphapar- through the wall and only 5% bounced ticleswere deflected, Rutherford concluded use a little petroleum jelly to form the back.
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