Thanks to Kathleen M (Spr 2016) for finding a fabulous animated gif that is 
connected to the Grid of Clocks from our lecture discussions.
 
 • Animated GIF illustrating the difference in local clock rates
   near a mass. This is a great illustration of "lower is slower"! 
   The graphic also looks like our "Grid of Signposts" visualization of 
   Schwarzschild coordinates (t,r,φ), but it is not ... it is the perfect 
   jumping-off point for further discussion of this important topic. :-) 
   The bending of the grid lines will also require quite some discussion.