According to research, “out of the different types of nonliteral expressions, idioms are the most frequently encountered in discourse. Without a knowledge of idiomatic expressions a nonnative speaker can never fully understand an English movie, sitcom or even the news” (Burke, 1998: 149). The aim of this study is to investigate how secondary school teachers work with idioms in their teaching. Additionally, the aim is also to see whether or not there are any differences regarding teaching at a secondary school in contrast to a high school. The method of choice is semi-structured interviews. Four secondary school teachers and four high school teachers were interviewed. The material in this study are the interviews, which have been recorded and transcribed. The results show that half of the secondary school teachers work actively with idioms through different activities. The other half stated that the teaching of idioms becomes a natural part of learning when the students read. The main difference between the secondary school and high school teachers’ approach to idioms is that the secondary school teachers put more emphasis on working actively with these types of expressions. Out of the four high school teachers who participated in this study, only one teacher focuses on the teaching of idiomatic expressions.