The scope of this article is to understand to what extent Computer Science teachers can find support for their Pedagogical Content Knowledge (PCK) in teaching material. We report the results of a study in which PCK is used as framework to develop a research instrument to examine three high school computer science textbooks, with special focus on programming. PCK is analyzed in this study in its two components: pedagogical knowledge (PK) and content knowledge (CK). The results of the textbooks have been compared with the results of a previous study, in which experienced teachers from various countries were involved in semi-structured interviews to portray the PCK of programming for secondary school. Our expectations to find textbooks relatively strong on the CK, but weak on the PK aspect, is confirmed by the results.