Last year, we did this project the first week of class and I decided to do it again today. It's a fun activity that also reinforces the importance of making prototypes and testing design along the way.
I have some playing cards with Rock, Paper, Scissors on them, so as they walked in today, I handed them cards. Then, they had to find their matches to form groups. I carried this forward to playing RPS to determine the group leader, too. A student suggested I give "rock candy" to the winner; man, I didn't think of that!
The instructions I used, with the built-in timer and the debriefing video, are all embedded into the presentation below. You'll also find some pictures from my top teams today.
If you'd like the Slides presentation, click here. If you wish to use it, just click File> Make a Copy and you can save one to your own Google Drive to edit.