Depending on your number of participants, either have everyone get into a circle or split the group into teams each forming a circle facing each other.
Ask everyone to hold their hands behind their backs. Highlight to everyone that this is a silent exercise so there will be no talking. When you say go, the group in each circle are to hold zero to 10 fingers each. The team that has 21 on their fingers first is the winning team.
It’s interesting to see how the teams choose to communicate silently without talking. Follow up the activity by discussing with the group how they felt about not being able to talk during the activity. What kind of non-verbal communication did they use? How can not being able to communicate clearly affect us back on the job when achieving tasks?