This thesis examines change of classroom climate in lower secondary school. In the theoretical part, issues of classroom climate, experiential pedagogy, adaptation courses and form teacher lessons are described from the perspective of different authors. The thesis introduces basic approaches for diagnosing classroom climate. It also gives instructions for management of form teacher lessons. B-3 questionnaire determines the current classroom climate and subsequent effects of the adaptation course among the respondents. Form teacher lessons are reported in this thesis, whose effect is also measured by the B-3 questionnaire in a longer period of the adaptation course. The results of the questionnaire investigation point to the need for regular...