Data on the students’ acquired knowledge were provided by pretest and posttest, which
students took before and after they learned about volume, mass and density, respectively. To
successfully understand density, one must certainly understand the concepts of mass and
volume, so tests contained questions that reflected students’ understanding of mass and
volume. The first question about mass was straightforward:
“Try to explain what is mass of a physical body, and write down the unit of mass.”
This question was asked because its results could be used to give insight into the
situation with the obtained declarative knowledge about concept of mass. However, it does
not give insight into students’ true understanding of it. To overcome this problem, test
contains open-ended questions which treat students understanding of concept of mass from
different aspects.
Next question related to mass was:
“What do you think, what has greater mass, 1 tonne of iron or 1 tonne of feathers?”
Answers to this question can reveal presence of students pre-conceptions of
"heaviness of materials" and comparison of masses of different objects by comparison of its
volumes. It can also reveal whether or not students have in depth understanding of the concept
behind which double pan balance operates.
Presence of students’ misconception on connection of sinking or floating of an object
and its mass was tested with the following question