In the article, we focus on the investigation of the disciplinary literacy of technical university students with an emphasis on understanding the mathematical language and symbolism in the tasks assignment. As part of the pedagogical research, we were looking for an answer to the research question "How do students interpret the misunderstanding of the assignment?". In the first phase of the research, the students solved a test that contained four pairs of mathematical tasks: a standard task and its equivalent, which required the mastery of mathematical symbolic language at a higher level. In the second phase of the research, students filled out a questionnaire that contained possible causes of failure in solving tasks in the test. Based on the research findings, we can state that the teachers and students agreed on only one item of the questionnaire, namely that the primary cause of the students' failure was a misunderstanding of the assignment. Teachers and students differed statistically significantly in their responses to the other items of the questionnaire. Based on the students' statements, we conclude that their understanding of the assignment of the task corresponds with the ability to assign the learned calculation procedure to the task, that is, with procedural knowledge. Teachers attributed the causes of student failure in the test to insufficient knowledge of the mathematical language.