Textbooks are highly structured objects, which are easily distinguished from other types of publications such as popular science books or academic works. This recognisable shape results from section-specific formatting, and layout standardisation. Yet these structures change over time and differ according to school disciplines.Our aim is to understand textbooks (specific resources) in themselves and grasp their evolution dynamics. Our approach here is to examine textbooks in both descriptive and analytical ways, using a comparative approach, and focusing on science high school textbooks, over a period of 20 years. The main questions steering our analysis are: What are the basic components of these textbooks? How to identify elements that are common to various school subjects or stable over time? What trends seem to be emerging? We have sought to highlight – via an analysis of school programme changes – some shared features that shed light on the directions that these school subjects and their supporting resources seem to take
