A comparative study has been undertaken of five post-millennial dissertations in Science Education in order to discuss the possible implications of their theoretical perspectives on practices in comprehensive schools. These theories include individual constructivism, sociocultural constructivism, social constructivism, theory of variations and combinations of these theoretical approaches. Even if these theories mainly are focused on learning, they might render tentative hints on acts of teaching. The theory of variations shows how questions might open up for activities which are not directly apparent for a teacher and the theory points out that it is fruitful to present the content of the subject matter in different ways. The sociocultural constructivistic theory focuses on communication between participants and shows how utilization of artefacts might create possibilities for enhancement of learning. The theory for individual constructivism sheds light upon processes of intrapersonal learning. Three different paradigms, emanating from these dissertations, are discussed in relation to school context, they are: acquisition, participation and constitution. It might thus be fruitful for teachers in comprehensive schools to study the contents of these dissertations and to reflect upon how these aspects of didactics could shed light upon teaching and for example to be able to take into account the differences between first and second order perspectives. The future development of didactics seems to lead towards hybrids of these Grand Theories in which for example a change from a dualistic towards a non-dualistic perspective on the relation between subject and object might be fruitful to take into account.