I agree with selfAdjoint. And, in no small measure because I've taught both SR and GR; SR many times -- from college freshman to advanced QM; GR only once.
Because of my strong empirical leanings, I tend to teach and understand starting from basic phenomena. In teaching, I'm no great fan of formal axiomatic approaches -- whenever I encountered this approach as a student or as a professor, I always wanted to know, "Where did this stuff come from?" And, my experience as a teacher strongly suggests that 1. simple is good; 2. history is important, 3. to generate good understanding focus strongly on experimental evidence, tough homework problems, AND student proclivities, problems and triumphs -- get students involved -- of course, in an appropriate manner. After all, a teacher will have no success unless his students have success -- I say this because, although it's not rocket science, too many teachers pontificate, play the grand old man, play the ego game, and forget the students as soon as the lecture is over.
Given my druthers, I prefer to teach SR in the context of E&M(at the graduate leve)-- that's where it came from. I used Jackson (primary text), Panofsky and Phillips, Landau and Lifschitz, I distributed my lecture notes, and ... My sense was, and still is, that students need to find their own way to understanding. Teachers can only serve as guides with helping hands -- I always pushed students to read as much as possible from as many authors as possible; to do more homework than assigned, and to develop their own style of working and understanding.
Space-time diagrams? I could care less. Of course an SR student should learn about them, be able to work with them.(I've never used them much, probably to my detriment.) But whether they are of use to a student is quite another matter -- best for you does not necessarily mean best for the student. Give students different approaches to basic SR issues -- like getting to E = M**C*C. What's important is that E does equal M C squared. But every derivation, has some sticky points, so deal with the sticky points; show the students the landscape rather than a narrow path, and focus on the experimental evidence -- that's why the equation is justly famed.
Teaching SR to freshman can be tough, particularly in a non-calculus course full of pre-meds. But it is invaluable to doing a good job with upper classmen graduate students -- freshman will bolster your intuitive understanding of SR (or QM, or...) and will thoroughly test your teaching chops.
I've also taught SR in both undergraduate and graduate mechanics -- spent less time on Maxwell, and more on Einstein's wonderful approaches and insights to get to relativistic mechanics. At Tufts, where I taught, we carefully worked out what parts of SR would be emphasized in what courses. SR is a huge subject -- lots of picking and choosing is necessary.
From a teacher's point of view, it is, I think, highly important to stress that there are regional dialects of SR and, probably, GR as well. pmb_phy's threads on relativistic mass offer positive proof of this. Make sure that students are exposed to basic conflicts and arguments. (What I think is profound, someone else might find bana.)
Teaching, with all due respect, involves much more than a few key points about approaches to the LT or whatever -- you might use up, say, three classes with a discussion about the LT and where it comes from... But how much time and emphasis on contractions and dilitations, and do you do this formally or a la Einstein of both... How will you deal with E = M**C*C?
Covariant notation? How much on particle physics-like kinematics? How much on SR related experiments done after WWII, ...Homework and exams... What balance between math and intution? ...
(I must say that my perspective seems quite different than many here. I think of SR, as do many physicists, primarily as a tool. Are there funnies, conflicts or contradictions or uncertainties about SR -- background, no background --, well that's life. From my training and experience I judge SR to be very reliable, so I don't worry much about many of the subtleties discussed in this thread. That's a matter of taste, interest, and mathematical skills. Godel said, in so many words, consistency in human thought and logic is nothing but an illusion. Physics is no exception, and many of us live quite comfortably in the face of logical contradictions and uncertainties.)
Regards,
Reilly Atkinson