Immerse children in any kinds of poetry that the teacher enjoys. Read several poems at nap time. Look for the book, Poetry Writing Handbook by Lipson, published by TLC Teaching and Learning Company. It teaches how to introduce poetic forms to middle school age children and is a good resource book for teachers who want to learn more about teaching poetry. Try making up rhymes.
Teacher writes and reads back each child's words.
Teacher listens for unintentional poetic word usage by kids and writes it down. Teacher writes down phrases of ordinary child conversation and reads it back as free verse poems. Capture the phrasing that is unique to children. Write the dialogue you overhear between children in short excerpts. Make up new poems about yourself or each other from the patterns in nursery rhymes and mother goose.