Abstract
This paper analyses linguistic features of primary school textbooks for the penultimate and final grades (grades five and six) and junior high school textbooks for the first and second grades (grades one and two), in order to reveal factors affecting the so-called "primary-secondary" learning gap. We chose science textbooks and analysed their complexities from the points of view of lexical and syntactic characteristics. The analysis revealed that there is a clear gap in syntactic complexities of sentences between primary and secondary school textbooks. The analysis showed that the factors constitute the gap between primary and secondary school textbooks.
