Swedish students' interest in science subjects in school is dwindling, so the purpose of this study is to research the relationship between how classroom tasks in the natural sciences affect students' intrinsic motivation, which is observed by their degree of engagement in the learning activity. By defining the content and function of the term scientific concept, a definition of scientific concepts is established within the study. This is viewed from the perspective of an increase in conceptual understanding through the use of engaging activities, as well as the effect of education.

Empirical data were collected through three semi-structured group interviews, with three teachers of natural science in middle school education, as well as through the use of a previously conducted learning study consisting of three cycles involving three classes with the concept of combustion as the learning target. The theoretical framework is variation theory, alongside aspects of Self-Determination Theory, specifically intrinsic motivation.

Results show that teaching practices require a high level of reflection and varied methods of teaching, both being essential for high learning outcomes in students. A high level of subject proficiency in the teacher ensures greater possibilities for student learning, due to higher levels of understanding in the subject, as well as an understanding of the difficulties students encounter in their learning. By connecting especially abstract phenomena to everyday understanding and lived experiences, students' sense of coherence and ability to manage the topic is increased, which is an important aspect of maintaining and increasing student engagement in the natural sciences.