"Masking": You may want to divide the group depending on it's size and sensitivity. The group stands in a relatively small circle. You can start in the middle making a face, a gesture and providing a voice. The idea is to be as silly and uninhibited as possible. Keeping your face and movement and sound you then pick someone out in the group move over to them and stand in front of them until they accept the mask by mocking your sound, face and movement. You are "passing" the mask to them. it should be like looking in a mirror. Do not switch places with them until you are satisfied that they are fully wearing the mask. This person goes into the center of the circle wearing your mask, transforms into some other being and then passes it to someone else in the circle in the same manner in which you passed it. Encourage students to make a clear transition, to really think about transforming from one silly creature to another. It is best to start this exercise, and every exercise, by modeling the masking for them. Not only does it give clear directions but it helps to ease everyone's inhibitions. Everyone should have at least one exchange.
* You may want to try again being different animals, plants heavenly and earthly bodies.