Worldwide, a tendency is visible in which upper secondary science curricula are innovated in the direction of context-based education. Crucial to these innovations is the way teachers interact with newly developed teaching materials and implement them in classroom practice. The focus of our research is to identify characteristics of the interaction between innovative context-based materials and teachers that hinder or facilitate classroom implementation as intended by the designers. Four cases of classroom implementation by four experienced teachers with different degrees of experiences in context-based education, all implementing "Chemie im Kontext" (CHiK) teaching materials, were carried out using a previously developed framework for analysis. It was found that a crucial aspect of CHiK, that of taking students' questions and using them as an orientation as the "focal event" for the following lessons, was difficult to implement. The employed contexts are too general and broad to be effectively applicable as a setting in which activities such as students developing their own ideas and exploring them logically take place. Therefore, it is recommended that extensive teacher professionalization is required on this aspect to show teachers its value and to increase their repertoire of necessary teaching activities. (Contains 4 figures.)