Strategies of Secondary School students to estimate density

Abstract

Density, or concentration of matter, is a central concept in science, and yet creates many learning and comprehension difficulties. To estimate how competent Secondary School students at estimating density are, we administered a 4-item questionnaire to 196 students at the 4 courses in two schools. Our results suggest that the estimation of density is dependent on the quantity and quality of sensorial information available - perceived weight, size or viscosity-, which sometimes lead to wrong estimations. In all levels, more than 40 % of the students treated density as an extensive property; around 50 % used intermediate models –sometimes inconsistent– closer to the idea of density as an intensive and specific property. The students had difficulties to predict changes in density with the state of aggregation or temperature, which calls for changes in the way density is taught.