The purpose of this study was to determine the relationship between the basic concepts related to the unit of "Chemical Reactions and Energy" and the sub-concepts underlying for meaningful learning of the unit and to investigate the effectiveness of them on students' learning achievements. For this purpose, the basic concepts of the unit were correlated with the concepts of previous units. The study involved fifty-two 11th grade students who were randomly assigned to the experimental and control groups. Before the instruction, a preparatory course was applied on only experimental group to remedy students' the misconceptions and lack of pre-knowledge identified by the concept test results and the literature reviews. After the preparatory course, the experimental and control groups were taught by the same teacher with the same instruction. The achievement test and interviews results showed that the experimental group significantly had higher scores and fewer misconceptions than the control group. (Contains 4 tables.)