Here and there phonoblog has links to teaching resources for phonetics and phonology. I have one to add: a recent concoction that I’ve developed to illustrate the goings on in a chain shift of vowels. In trying to put myself back in the shoes of an undergraduate, I was imagining that seeing a static vowel chart with arrows leading away from IPA symbols might be a little cryptic. (Especially in a lower-level class about language and society in which I’m not pushing them to learn IPA through and through).
Turns out wicked little Powerpoint now lets you move existing slide objects around with its animation tools, which I decided to take advantage of. I have posted some examples for you to check out: the idea is that words (representing phoneme classes) move in two-dimensional vowel space when you advance the slide. (I used words since moving the phonetic symbols is uninterpretable).
The examples are the Northern Cities Shift and the Canadian shift. In the NCS, I do not commit to a push or pull chain, but the Canadian animation suggests a pull-chain precipitated by the low-back merger. The fronting of /u/ is also to be taken with some salt; I have heard it from many Canadians, but by impression is that it has not quite arrived in the quirky little dialect of Urban Eastern Ontario English that I speak.
The Canadian slide also demonstrates a bit of a problem with the approach: limited dimensionality. Since the slides only manipulate height and backness, but not length or roundness, they risk illustrating a non-existent merger. (This is why I left off my Scottish vowel space). It is also difficult to illustrate diphthongs and monophthongs, which is why I left off my Southern vowel shift.
I’m leaving the comments open, so if you think these are (a) cool or (b) dumb you can say so.
The slides are in Office 2003’s PC version of Powerpoint, so I apologize if your platform doesn’t display it well.
Note that I had implemented a similar idea with an animated gif in the Language Samples Project, but constructing these is fairly time consuming. Also: the st__ck series is one I find particularly illustrative, and I found in it a paper by Charles Boberg.