Date of this Version
Students were asked to categorize 13 previously collected samples into 4 groups. Ideas on what properties should be used to categorize the samples were left open to the students. It was found that properties dependent upon the method of collection would make more than 4 groups, therefore properties dependent only upon the material were used in the categorization. The central idea of this activity is to confront the student with the requirement to quantify his concrete experience with materials of different densities. Density, since it involves ratios, requires formal operations. This experiment begins with a task that will hopefully induce some disequilibration, followed by the opportunity for self-regulation.