摘要：The aim of this study is to analyse and compare the mental models of grade-7 students
concerning the atom concept before and after instruction. The study was carried out in 3 elementary
schools with 217 students attending grade-7 before and 215 students attending grade-7 after instruction.
The data was analysed by using word frequency counting or simple percentage counting basing on the
student answers. The results of the study show that grade-7 students cannot sufficiently comprehend
and visualise the structure of atom and they have various disequilibrium and misconstruct some
phenomenon even though they make some progress after the training. More than half of the students
thought of atoms as solid spheres before the instruction and half of the students constructed the Bohr
Atomic Model that was used in the textbook to explain the structure of atom after the instruction. At
the end of the instruction, only 5% of the students managed to construct the Modern Atomic Theory
that is valid today. A small part of the students before the instruction and nearly half of the students
after the instruction stated that atom cannot be seen. It was observed that both at the beginning and the
end of the instruction, students compared the size of atom with small visible things like lentil, ant, etc.
