High school students' schooling is preparing for their future. It is therefore important that their school time is characterized by security and a good physical school environment. The purpose of this thesis is to investigate how the physical school environment outside the classroom affects the safety of high school students. The aim of the study is also to highlight a possible connection between how the design of various places in the school affects the safety of the students, connected to where the students mostly stay during the school day. Previous science and background facts about safety in the physical school environment emphasize how important it is with the school's design. There are numbers of relevant factors to consider when designing a school and how to promote security in the physical school environment. To be able to answer the issues of the thesis, quantitative surveys have been sent out to high schools students at a secondary school. Through bar charts, the result is presented and then analyzed based on the method bivariate analysis. The theoretical framework of the thesis consists of Simmel's sociological theory and the spatial theory perspective. The results of the study are analyzed on the basis of the theory perspective and compared with previous science and other background facts. The results of this study shows that students are safest in the dining room, the library and in the places where they mostly stay daily. The factors that contribute to security are mainly that people they feel safe with are there, open spaces and comfortable sound levels.