Be prepared with a list of things for everyone to imitate, e.g., juice going through a straw, a bee landing on a flower, or popcorn popping. As you call out each item on the list, ask the children to stand up and invent their own imitations. Remind them to look around at their neighbors' interpretations, too. Encourage general silliness and invite children to make suggestions of things to imitate.
You can also have children work in pairs. One child moves and the other child narrates a story about what the partner is doing. If time allows, have the partners switch roles.
