Basically yes, when the textbook or parts of it have creative and individual elements. The form of representation in particular can be protected, i.e. the structure of the textbook, the way the contents are put together, the form of linguistic communication (e.g. through images, tables, diagrams, etc.), the language itself (e.g. for laypeople without specialist vocabulary or humorous descriptions).However, the (teaching) methods or the knowledge about them which is transmitted by the book are not protected because parts of already known, tested and researched matter are summarised for the purpose of knowledge transfer.