Instruct your whole group to walk randomly around the room. About every ten seconds or so, call out a number and an (appropriate) part of the body. Players must immediately form a group of the number called, with everyone connected in a circle or a line by that body part, e.g. line up shoulder to shoulder.
For the last round, call out the number that will give you the right amount of small groups you want for the next activity (e.g. “Five, Elbows!”.)
Appropriate body parts are heads, shoulders, knees, toes, elbows, wrists, (even hands – if you dare!).
Heads and knees provide more of a challenge so keep these for later rounds.
To add to the fun and motivation: each round, have another leader spot which group were first to form and each participant of the winning group is given a matchstick. After several rounds the person with the most matchsticks wins the game. Declare them the most connected person in the group!