We investigated students’ feelings and well-being during the lesson. We were working on a problem of how to adjust teaching in the secondary school and achieve that students will feel as good as possible and better follow the instruction. A hypothesis was set that, by measuring the desired length of lesson and factors which influence lesson length, we can measure and influence student satisfaction. Based on this hypothesis we investigated the factors which have influence on lesson length in a particular subject. Data were collected by means of a questionnaire. The subjects were students ofII. gimnazija(secondary grammar school). The responses were analysed to obtain correlations between the factors (average grade in a subject, boredness and likableness of the teacher, length and level of boreness of lesson content, fear of the teacher) and lesson length. Results suggest that, by modifying these factors we could change students’ opinions, that is, increase their willingness to attend classes. The set hypothesis was confirmed and it was shown that by using simple diagrammatic models built on the basis of linear regression we can identify and study the influence of these factors on lesson length.