The results presented in Table 7 indicate some interesting trends:
• The percentage of students who provided a correct answer both before and after the basic course is relatively low and does not exceed a total of 50%.
• For all items, except ‘molecule’ and ‘temperature’, most students provided answers that were categorized as partially correct, i.e. containing some correct elements, but not accurate or complete answers.
• In general, students tend to explain concepts at the macroscopic level more than the molecular one, both pre and post the basic course.
• Chi2 analysis revealed that for all concepts, except molecule, there is a significant difference in the distribution of answers pre and post the basic course.
In cases where a significant difference was found, a post-hoc multiple comparison in sample proportions was conducted in order to identify the causes for the difference in distribution (Marasculio and McSweeney, 1977).
It was clear from students’ answers, at the end of the basic course, that they have more knowledge regarding specific items, and that they use a richer chemical vocabulary. However, their answers demonstrate that most of them could not use this knowledge correctly.