Guess who the ghosts are - who are covered with white sheets!.
Divide the group into girls and boys. First take one group out of the room and put a white sheet over one of the children. Take the covered "ghost" back into the room and let the others guess who the ghost is. Continue until the first group has gone. Then switch groups and start again i.e. if boys went first, then take the girls out and let the boys guess.