This paper analyses how lower secondary pupils experience their participation in the Danish science and green entrepreneurship competition, called Edison. The study uses a qualitative research method to investigate pupils' descriptions, in retrospect, on the process of their entrepreneurial work. We completed semi-structured interviews with two teachers and six groups of pupils from two schools. Independence and being able to determine their own product were motivating factors. Often the pupils included other actors, particularly family members, on their own initiative as part of their work. The pupils' interest in STEM education did not appear to have been affected except for two pupils who broadened their educational perspective. However, the awareness of sustainability issues has for some of them been supported, one of them with a change of lifestyle. By including engineering design process models in the analyses, the concept of entrepreneurship in science and technology became more process oriented and operational, which may also help both the teachers' facilitation and the pupils' inventing process.