Once your students have a good basic understanding of how to use their voices technically and creatively, get them working in groups, perhaps on a short poem to see how they can turn this into actions. They can rehearse this on their own and show you what they have discovered in the next class. Alternatively, you could work in the dark with the students lying on the floor, releasing sounds and exploring their voices collectively. They will feel less self-conscious that way. Once they are vocally confident, combine this with more complex physicality: set them some Acrobatic exercises and notice how engaging their breath can help them feel at ease and better feel the rhythm of these exercises. Can they do a basic acrobatic exercise whilst reciting a line of text?