Liberal arts chemistry students often struggle with the application of the scientific method to problem solving in the sciences, in part because of insufficient concrete examples. These same students also tend to have significant difficulty in appreciating the value of weight ratios in chemistry, particularly in the establishment of the laws that led to the atomic theory. A simple classroom exercise utilizing net weights of envelopes containing varying numbers of BB's or paper clips can be used to illustrate and differentiate the steps of the scientific method: observation (with corrections) to get scientific facts, induction to arrive at laws, tentative explanation by hypothesis, experimentation to test the hypothesis, and final establishment of a scientific theory. Since the students participating in this exercise arrive at each of these steps on their own, there is greater appreciation and more effective internalization of the scientific method on their part. The exercise depends upon the discrete nature of the BB's or paper clips (i.e., on the fact that they are individual "particles" of similar properties, and so are useful analogies to atoms). Finally, since weight ratios are used to solve the problem posed by this exercise, it can be used to lead directly into the weight ratios summarized by the laws of constant composition (fixed proportions) and multiple proportions, which in turn lead to Dalton's atomic theory.
More Information
Citation
Hohman, James R. J. Chem. Educ.1998 75 1578.
Keywords
Demonstrations; Introductory / High School Chemistry; Nonmajor Courses; Teaching / Learning Aids
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