In Slovenia, the RINOS working group has proposed changes to the curriculum and the introduction of computer science (CS) as a compulsory subject in accordance with the K12CS framework. An important step in the introduction of the subject is the development of new teaching materials and environments for teaching CS. Currently, most Slovenian materials for teaching CS are collected in the Lusy library. These include e-textbooks, materials for teaching CS, booklets of tasks and solutions, systems for various CS competitions, and platforms supporting practice of programming. Good teaching materials for CS should be relevant, interactive, easy to navigate, and promote active learning. Because CS education is a relatively new field, its didactics is almost constantly improving. Therefore, it is necessary to prepare teaching materials that can be easily modified, adapted and used for active learning. Various teaching materials with these properties can be found in the Lusy library. We conducted a qualitative survey among teachers of CS to assess the usefulness of existing materials and environments for teaching selected thematic units and to gain insight into teachers’ needs. Our findings will provide the basis for developing useful practical teaching materials and activities for a future compulsory subject.