Often participants who are acquainted with or know each other well choose to sit next to each other in the classroom. To split up the group in a random way (if the facilitator wants groups with participants who do not know each other well), the facilitator may use the following method. If the aim is four groups, he/she can ask the person in the first row (or at the first place in a horse shoe) to say ONE, the next person says TWO, the next THREE, the next FOUR, before the next person continues with ONE, the next with TWO and so on. When finished, the facilitator asks all the ONEs to gather in a group, all the TWOs to gather in a group and so on.
A simple way of dividing participants into smaller groups can be to draw lots with a group number. The participants who draw the same number will be in the same group. An alternative and a more fun way to do this is to use symbols (fruit, animals etc.) instead of numbers on the pieces of paper. Then all the "oranges", "apples" or "cats" go into each their group.