This paper reports on the results of the first phase of an ongoing research project in design-oriented education in informatics in Dutch upper secondary education. Our study focused on eliciting and categorizing the pedagogical content knowledge (PCK) with respect to design of digital artefacts of the informatics teachers participating in the research project. Our results suggest that teachers´ PCK on design can be typified in terms of two aspects, namely (i) teachers´ knowledge about objectives and goals of designing digital artefacts by students, and (ii) teachers´ knowledge about ways to assess students´ understanding and performance. As to (i), we distinguish an orientation towards more conceptual objectives, and one towards more practical objectives. Also with respect to (ii), we found two types of teachers´ knowledge, one focused on process-based assessment and another on product-based assessment.