Teachers need creative strategies and techniques when teaching idioms in Setswana. However, they do not know what idioms are nor are they aware that through idioms cultural heritage can be preserved and that idioms can be taught as part of imaginative language, especially in Grade 3. As a result, teachers and learners in Grade 3 Setswana classes lack the understanding of the role of idioms and language proficiency in using and writing idioms. The aim of this paper was to show how intervention could help teachers with new strategies for teaching idioms. Constructivism and the five subtheories of decoding idioms were used (Liu 2008). The project consisted of two research-based phases and the findings showed that teachers can now use their own initiative and creativity in language teaching and the learners learned and retained the idioms they have learnt.