The Drinking Bird and the Scientific Method Introductory lectures of a general chemistry course customarily attempt to define the "scientific method." We have found that a simple toy,' the "drinking bird," can provide a puzzling phenomenon which can be used as a model to illustrate the basic processes of a seientific investigation: data gathering, synthesis, and application to p r a c t i ~ e . ~ The experiment is reminiscent of Campbell's classic blue bottle experiment,= in that students actively participate in formulating the observations, hypotheses, and conclusions regarding the phenomenon. The toy is constructed as shown in th6 figure accompanying the previous article.' A small glass bulb, partially filled with a red liquid, represents the hird's tail and abdomen. Extending from this bulb is a glass tube which rises to the "head" of the bird. The exterior of the head is covered with felt. A metal band attached to the glass tube acts as a pivot and allows the bird to rock. The hird is first assembled without wetting the head of the bird. When rocked on its pivot, nothing much happens; the bird s w n stops moving. When the head is wetted, however, the bird continues to rock when set in motion as the red liquid rises u p the tube to the head. Eventually the bird becomes top heavy and tips forward. allowing a bubble to enter the glass tube, displacing some of the red Liquid back into his tail. At this point the bird resumes an upright pasition and the cycle continues (if a glass of water is situated in front of the bird, it apparently takes a "sip" and rocks backward). The class was first invited to describe the phenomenon as accurately and objectively as possible. One student described the system as a "pump" and another as a "syphon." Both suggestions were criticized by others as premature explanations rather than simple observations. After the "cycle" of the bud's action was monitored and described, a hywthesis was put forth: the red liquid was rising because the tail was warm in relation to the head of the hird (which &being dunked into cold water). Various experiments were suggested and tried. Would the bird bob if the head were heing soaked in hot water? The hird continued to rock. If the tail of the hird was heated. would the liquid rise faster? The liquid rose rapidly as the tail was hand-warmed. Obviously, a temperature differential between ;he head and tail was responsible for the Liquid rising. In response to another suggestion, the hird's head was filled with the red liquid, and the hird was then inverted and its head immersed in warm water. To the initial puzzlement of the class, the red liquid did not rise. One student noted that the system was changed by inverting the bird, that in an upright position the vapor was heing heated, but in the inverted system, the liquid, rather than the vapor, was heing warmed. There was an immediate suggestion to warm the head of the uprighted bird with my hand; the liquid immediately slowed in its ascent. One student suggested that the evaporation of water from the bird's head caused the liquid to rise and hypothesized that if alcohol were used as the wetting agent the liquid would rise much faster. This was proved immediately. In summary, this simple device provided an excellent means of establishing a rapport with a new class, by involving them in the processes of thescientific method. 'Another version af the same tov dresses the s .~.~ a r a t as u sa drunk in top hat and tuxedo. The toy can he purchased at mast novelty stores. Xassidy, Harold G., "Science Restated: Physics and Chemistry for the Non-Scientist," Freeman, Cwper and Co., 3Campbel1, J. A., J. CHEM. EDUC., 40,519 (1963). T w o weeks before this note was sent in, Robert Plumb submitted an Exempla for his column entitled "Physical Chemistry of the Drinking Duck," [J. CHEM. EDUC. 50, 212 (1973)l which deals with the phase equilibria and thermodynamics of the toy David L. Frank California State University Fresna. 93710
Volume 50, Number 3, March 1973
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