In foreign language teaching, the transmission of the culture within which the target language grows is as important as teaching new words and grammar. All elements of the culture have their own special places within the vocabulary of the language. Reflecting not only the linguistic structure but also the culture of the society to which they belong, idioms pose utmost importance for foreign language teaching. The aim of this study is to determine the level that Turkish as a Foreign Language students use the idioms they have learnt in the class while writing. To this end, the idioms covered in B2 and C1 level Turkish as a Foreign Language course books have been specified, and the frequency at which the students use these idioms on their writing-based exam papers has been determined. Therefore, the questions whether the students are able to use these idioms or not, and if they do, what type of idioms they prefer to use in terms of semantics, have been addressed within this study. Following that, samples of linguistic activities that can be employed for teaching idioms have also been proposed hereby.