Lecturing again to high school class, on systems thinking relevant to their current project to design a bridge. Eased into systems levels and pacing with a personal story about family and service systems at home. Whiteboard discussion on bridge led to a question: will animals be permitted to cross the bridge, or will they be prevented from following their nature? (Tongji Huangpu School, Middle Sichuan Road, Waitan, Shanghai, PR China) 20180423