The relatively high means for most categories (around 2.5), presented in Table 5, indicate that most of the students were already familiar with many chemical concepts at the beginning of the basic course. This is true especially for concepts included in the following categories: scientific inquiry, sub-micro concepts, general types of substances, and specific materials. It is suggested that many concepts in these categories were familiar from science studies in middle school (for example: atom and molecule), and from daily life (for example: air). Concepts that were included in the ‘Chemical reaction’ category were less familiar to the students (mean 2.1) at the beginning of the basic course. No significant differences were found regarding the categories ‘General types of substances’ and ‘Specific materials’. This can be explained by the fact that many items were already rated at the maximal level in the pre-test by most students, especially in the category of “specific materials” (items such as air, ozone, and metal), whereas other items were less familiar at the beginning of the course and remained that way, since they were not addressed in the syllabus of the basic course and were not discussed during the course. To sum up, comparing the results of students at the beginning of the basic course (10th grade) and at the end of it (same classes) revealed a significant improvement in students’ acquaintance with concepts included in three out of five categories.