This paper deals with the issue of mobile phone usage through analysis of high school students' opinions of using mobile devices during class and outside the classroom, which determines the frequency of their use, as well as the correlation with learning and student concentration. We can say that changes in the environment of young people directly affect on their behaviour inside and outside the classroom. The research was based on determining the correlation between high school students' concentration during learning with the use of mobile devices during class and outside the classroom. The main goal of the research is to analyze opinions and behaviours of young people regarding the use of mobile phones during class and outside the classroom. By polling the students, we got the results about student's mobilephone use and types of using them;we determined the frequency of use and the purposes students use mobile devices for during class and outside the classroom; we have questioned students about the use of mobile applications and social networks and how often they use them; we have determined which consequences the use of mobile phones during class can leave on the student's activity and listening in class; we examined students'views about the positive aspects and the negative aspects of using mobile phones during classes; and we have determined whether students are using mobile phones at home during learning and for what purposes.