This study explores the stability of the knowledge gained during lower secondary science instruction. This implies to elicit the conceptions resulting from science education and to study the restructuring processes afterwards. Two groups of students (10 students each) had been distinguished by their learning behaviour during science instruction. They were investigated in a pre-post design over the period of one year using in-depth interviews and questionnaires. Findings suggest, that consciousness about the two domains of everyday and science knowledge is a good precondition for a comprehensive, precise and coherent knowledge, especially for stability of the majority of conceptions and - to meet the specific topic - for stability of microscopic thinking. However, this metacognitive orientation does not protect from punctual misunderstandings which appear to be stable as well.