This paper describes an investigation of primary education student teachers’ perceptions of computational thinking (CT) who participated in a course ‘Digital Technologies in Primary Education’, and explores what these students consider difficult when developing primary school pupils’ CT. In the academic year 2021/22, a revised curriculum will be introduced into Czech primary school education. Instead of ‘ICT’, ‘Informatics’ is to be introduced into the curriculum as a new subject at all school levels. Pupils’ digital literacy will be formed and developed across all subjects, so all faculties of education in the Czech Republic have paid great attention to the development of primary education student teachers, to prepare them for the planned changes in school practice. Using qualitative methods, the study findings of 66 primary education student teachers (who analysed the Bebras contest for primary school pupils) were that (1) for better understanding of CT, student teachers are required to have sufficient Informatics’ knowledge to be able to think computationally, (2) student teachers reported CT is close to mathematical thinking, but these two concepts are not the same, and (3) CT development in primary education requires logical thinking, reading literacy and counting abilities.