Stage: 1, 2, 3, 4 and 5 Challenge Level: 
A recent trip to a beach on the north-west coast of Scotland resulted in an engaging hour or so balancing pebbles. Exploring balance and centres of gravity can be great fun. The resulting structures can seem impossible.
Here are some images from Scotland to encourage you to experiment with non-breakable objects of your own.
Towering
Stones
Picnic
Birds of
Prey
Real world. Visualising. Working systematically. Centre of mass. Mathematical reasoning & proof. Logo. Introducing algebra. Practical Activity. Interactivities. Trial and improvement.
Published August 2009.
Copyright © 2007. University of Cambridge. All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project, which also includes the Plus and Motivate sites.
email: nrich@damtp.cam.ac.uk