In our research, we examined the data of students studying in non-baccalaureate vocational schools the National Assessment of Basic Competencies in 2017 and 2019 (Nmathematics: 11 776; Nreading: 11 582). In terms of the effectiveness of the school, one of the most important factors is the kind of work the teacher does, and it is also extremely important how constant the teaching staff is in a school, in other words, how much the teacher fluctuates. Our results did not fully confirm this, as we experienced higher efficiency in the case of higher teacher turnover. At the same time, there are results that support the results of previous research: a higher proportion of beginning, out-of-school and out-of-school teachers is associated with lower student achievement, but this can only be said in relation to the mathematics skill area. In the field of reading comprehension, the opposite trend prevails.