Everyone in the group thinks of a number from 1 to 3. Depending on the number they have thought of they will greet the others in the following way:
Number 1: Clap your hands with the other person once.
Number 2: Clap your hands with the other person and offer them to clap back.
Number 3: Clap your hands with the other person and offer them to clap back and hold your arms out for a high five.
Everyone moves around the room without talking. At the signal, they start to greet the people they come across according to the aforementioned rules. Those who greet each other in the same way form a group. (If it is important to have groups that are of the same size and to avoid having most people think of the same number, you can write the numbers from 1 to 3 out on pieces of paper – based on how many participants each group should have – and offer them to participants to draw.)