It sure would be a service to all organic students if someone were to create a good, interactive web page that draws from Hens' page and shows using Jmol the smooth transition from chair to chair via half-twist (I was calling this twist-chair) and twist (I was calling this twist-boat) as well as other possibilities (as through a half-chair and boat, perhaps). A nice reference to draw from is

http://pubs.acs.org/doi/abs/10.1021/ed074p813
A Three-Dimensional Energy Surface for the Conformational Inversion of Cyclohexane
Nicholas Leventis , Samir B. Hanna and Chariklia Sotiriou-Leventis
J. Chem. Educ., 1997, 74 (7), p 813
Publication Date (Web): July 1, 1997 (Article)
DOI: 10.1021/ed074p813

Bob