For those who haven't seen one of the "tire swing" cartoons mentioned in the article: http://www.projectcartoon.com/create/ http://www.projectcartoon.com/create

For those who haven't seen one of the "tire swing" cartoons mentioned in the article: http://www.projectcartoon.com/create/ http://www.projectcartoon.com/create/ and some historical versions: http://www.businessballs.com/treeswing.htm http://www.businessballs.com/treeswing.htm :)