The Marshmallow Challenge

drawn on iPad Mini using Paper app and Just-Mobile AluPen

The Marshmallow Challenge is an indoor, patrol-based, teamwork and creativity challenge that can be run with minimal equipment and twenty minutes of time.

Developed by Tom Wujec of AutoDesk (Producers of the FormIt app and AutoCAD amongst many,many others), this challenge has been used by large and small companies, schools and kindergartens, as well as scout groups around the world.
The rules are simple: each team has 18 minutes to build the tallest possible freestanding tower (i.e. Not supported by anything other than the floor) with the marshmallow at the top. My Rover Crew recently ran this challenge with every Scout patrol in our district. Here are the results as an idea of the heights that are possible:

Here is a video of Tom discussing the challenge and what it teaches about teamwork: