How do fifth graders understand the language of mathematics textbooks?

A significant and insufficiently studied problem in the education in our country is the quality of textbook language. It is vital to address the issue from students? perspective (to whom this teaching aid is primarily intended), which, among other things, enables to analyse whether the textbook presents the support for students to learn, but also to examine the extent to which the textbook can help students improve their basic abilities, primarily linguistic and cognitive. Therefore, the aim of this paper is to examine how fifth graders understand the language of mathematics textbooks. Students (N = 209) of the said age from three Belgrade primary schools participated in the research. The students were asked to mark language units whose meaning they did not understand in two lessons (studied and nonstudied) in mathematics textbooks. The results indicate that there are several types of linguistic units that students evaluate as incomprehensible: words, syntagms, and sentences. They also reveal that the students understand better the language of familiar than that of unfamiliar lesson, which indicates that they would not be able to master the knowledge from these textbooks independently. In the familiar lesson, significantly more students do not understand words and syntagms belonging to general lexical system of Serbian language. In the unfamiliar lesson, however, significant percentage of students does not understand meanings of the sentences used (seven sentences in average). The students with a better grade in mathematics marked fewer unclear sentences in both familiar and unfamiliar lesson. The obtained results could be used in improving the quality of the language in mathematics textbooks, as well as in raising students? language competence.