Mapping students’ knowledge structure in understanding density, mass percent, molar mass, molar volume and their application in calculations by the use of the knowledge space theory

Knowledge space theory was used for mapping students’ knowledge structures in calculating density, mass-percent, molar mass and molar volume. Data were collected among the 9-10 graders (age 15-16) at two different secondary grammar schools. Students’ responses were evaluated in a binary fashion and were used for determining knowledge structures with a systematic trial-and-error process using χ analysis. Based on the students’ knowledge structures, the critical learning pathways, the characteristic hierarchies of concepts and the critical concepts were identified and analysed. In students’ cognitive structure, molar volume is built on the concept of molar mass. With one group there is a strong connection between the concepts of density, molar mass, molar volume and the calculation of gas volume while with the other group there is no such connection. The reason for this disconnected cognitive structure is the difference in the learning method between the two groups. Students from the second school learned the concepts of density, molar mass, molar volume and mass percent by rote-learning using mnemotechnics. This is a good example that rote learning makes the finding of the connections between concepts hard and gives separated and non-mobilizable knowledge. [Chem. Educ. Res. Pract., 2007, 8 (4), 376-389.]