This study investigates, and further develops, a framework for analyzing technological knowledge emanating from school design projects; a framework that has the potential to be used as a tool for teachers when choosing and planning design projects. The study also intends to answer the research question: What technological knowledge, associated to physical models, emanates from design projects common in Swedish secondary schools. To answer the research question, the framework is used to analyze three design projects common in Swedish secondary schools. The design projects were video-recorded during actual classroom work by using a self-following robot camera. The projects involved three teachers and 70 students in grades 7, 8 and 9. Deductive content analysis of the video-recordings revealed that technological knowledge from four categories -- Technical skills, Technological scientific knowledge, Socio-ethical technical understanding and Engineering capabilities -- within the framework emanated from the three projects. A new category of technological knowledge was also found, namely Technological research capabilities. This fifth category is related to the capability to search for, and interpret, information about solutions when doing a design. An implication of the conducted study is that design projects are important to enable development of technological knowledge in the school subject technology. However, considering the amount of time a design project requires, there is only room for a few projects in secondary school. Therefore, technology teachers have to carefully choose and combine projects to educate technological literate citizens as well as prepare students for studies and future careers within engineering and technology.