Here I wish to play a bit with the "Twin Paradox" of Special Relativity. [*note, it ain't a paradox]. For this you'll need to be happy with (1) time-dilation, (2) length-contraction, (3) Lorentz velocity transforms and (4) straight lines. I like to draw things, so in the video I construct 3 space-time diagrams for the various reference frames of the problem. A pdf version of the 3 space-time diagrams can be found here: Sloan_Twin_SPACETIME so you can see the final versions.
The subtext to this is really it's a chance to put into practice some of the fundamental properties of Special Relativity outside their usual undergraduate use of simple problems. The logic I follow is hopefully step-by-step simple, but the picture we build up will be complicated. At the end the paradox will melt away, in fact it was never there in the first place.