Boldface links give quick local access. Other links lead to distant Web sites (and may be slow).
Review of class 2 by Sarah Salwen, class 3-1 by Michael Loatman
Hypercubes and higher dimensions:
Dali's painting "Corpus Hypercubicus" and links to other paintings.
Minkowski's space-time metric s2 = l2 - (ct)2, where l2 = x2 + y2 + z2, by Pythagoras.
How can a three-dimensional space be curved? See QA99
Roger Penrose, brief biography, adapted from http://rysy.msm.cam.ac.uk/~msms/penrose.html.