We co-design project-based learning units in order to support teachers’ professional learning. In co-design, researchers, teacher educators and teachers design, enact, and evaluate teaching units together. The units are digitally intensive and aim to increase students’ engagement and develop students’ physics and chemistry competence. Together with teachers, we evaluate the students’ experiences and learning of curriculum goals. Based on evaluation, new versions of the project-based units will be designed. As an outcome of this iterative co-design, enactment, reflection, and further design, pedagogical models for motivating PBL units and informal assessment will be developed.