Abstract
One of the main purposes of textbooks is the mediation of educational content to students. The factual accuracy of information, as well as the clarity of the text for students plays a crucial role in this aspect. The inadequate text difficulty can complicate students' learning. Comparing different approaches to the text in textbooks, considering the objectives of education, represents key knowledge for teaching materials innovation. This research was therefore focused on the comparison of the Slovak and Canadian science textbooks for lower secondary education. The methodology for assessing text difficulty according to Nestler, Prucha and Pluskal was used for this purpose. The samples of text from the textbooks for 6th and 8th grade of lower-secondary school were assessed. It was found that the text in Slovak textbooks is significantly more difficult. While from the syntactic difficulty point of view differences were rather partial, the significant differences were found in the semantic difficulty of the text. The Slovak textbooks are burdened with an excessive number of professional terms. Considering the results in measuring scientific literacy, this approach to the text in the Slovak textbooks is not effective. The results obtained are therefore an incentive to revise used educational materials.