Soup Can Races - Cover Sheet SCI Home | SCI Faculty Page | Case Notes | Reference List | Users Notes

Author - John Shepherd - Fall 1997, Spring 2000

Case Purpose This case provides students with a simple experimental demonstration: one can of soup (chicken broth) rolls down the ramp faster than another (mushroom soup). Observations from the demonstration must then be used in the evaluation of competing interpretations of the results to reinforce the interplay between observation and interpretation. After students have agreed on an interpretation, they are asked to design experiments that could falsify each of the interpretations (hypotheses).

Relation to Texts The case asks the students to apply the ideas of Logical Necessity Ziman discusses in Section 2.3 (pages14-16) as they consider the relation of observations and interpretations. Ziman starts section 2..5 by comparing the "primitive, exploratory" (phenomenological) stage of investigation with a more mature theory/modeling stage, and a last "decadent" stage of axiomatization. The students will spend the first part of this exercise in the exploratory stage and then move into the theorizing stage to varying degrees. The second part of the exercise ties together two other sections of the same chapter. As students are asked to design potentially falsifying experiments, they must predict what would happen under each of their experimental designs (cf, Section 2.8, Prediction, pp 30-33 ) and relate possible outcomes to the theory (Section 2.9, especially pp 35-38, The fit between theory and experiment.)

The revised worksheet tries to use this as an example of the four elements of a scientific episode (Giere Figure 2.9, p 30).  This simple model was surprisingly confusing last semester.  They confused the Real World with the Model, the Model with Predictions, Predictions with the Data, etc.  This exercise make make the distinctions more concrete.

Description of Case Materials The experimental materials consist of three soup cans and a long ramp. These are stored in the Biology storeroom. Call the Biology lab coordinator (Vernice Thomas x4138) to find them. A brief problem sheet asks the students to evalutate competing hypotheses about the results. A set of background material includes a description the physics that explains the results. There are both simple and complex explanations available. Revised worksheet for use with Giere Chapter 2.

Case Use Student groups are shown the cans and the ramp, and asked to predict what will happen when the two cans are rolled down the ramp side by side. Then the can race is run until all are convinced that one wins consistently. Groups of students are then given the exercise sheet, which asks them to evaluate three competing hypotheses for the results (or to make up a fourth hypothesis). After 15-20 minutes, groups report the results of their discussion. Groups are asked to design critical experiments to test the hypotheses. Groups are asked to critique/defend their experimental designs.

Reference List Patrick Briggs & John Swez. 1995. Instructor’s Resource Manual to Accompany FW Bueche & DA Jerde. Principles of Physics. 6^th ed. McGraw-Hill