The aim of this paper was to learn difficulties in assessing students' knowledge that teachers come across every day. What is more, it was equally important to investigate in what way do they deal with these difficulties, who helps them, do parents put teachers under pressure because of their dissatisfaction with the grades and are the students, in their opinion, satisfied with the grades they achieved. The conclusion is that the majority of the teachers has difficulties while evaluating students and that this is a very stressful part of the job. They understand difficulties in different ways, to some teachers a difficulty is the method of evaluating, student's handwriting, learning without understanding, not paying attention during the lesson or the lack of objectivity. They solve the listed difficulties by themselves taking in account regulated evaluation criteria, in that way there is less student dissatisfaction. Only on rare occasions they ask for help of their class teacher or the school's counsel guide because some parents are not satisfied with the grades, and that is because of the opinion that their child deserves a higher grade. Also, at the end of the year, teachers do a poll amongst students about contentment with the grades and the results show that the students are satisfied. It is important that the evaluation is done as objectively as possible, taking in consideration only the grade without other factors, and in that way the students will be pleased because they realize that higher grades enable desired continuation of education, what is important to them later in life.