When I work with comics in the classroom, it is almost always from a formalist perspective, looking at how the different elements that make up a comic work together to make the storytelling happen. Of course, there are other ways to study comics, and one of them is to look at comics as cultural artifacts that can tell us something about the time and place that they came from.
A rather obvious example of comics-as-artifact is the 1942 U.S. War Department publication Pocket Guide to China, which includes a section called "How to Spot a Jap," drawn by Milton Caniff, of Terry and The Pirates and Steve Canyon fame. Here's a sample page:
Um, wow, hunh? I'm going to be proposing a learning community combining an English class in US Literature Themes with a sociology class on American Ethnic Cultures, which will use comic books as a source for examples and illustrations of ethnic stereotyping. Stuff like this would certainly be appropriate for study in that class.
Of course, that example is a little bit of the tail wagging the dog, in the sense that the comic was produced specifically for the guidebook and was merely the channel to deliver the specific and deliberate message. It wouldn't be hard to find examples of similar stereotyping in genre comics, though; to wit:
But it is not just egregious stuff that we can find in comics; the little things, like fashion or fads or slang, are also preserved in those fading colored panels on yellowing newsprint. Take this little scene from Incredible Hulk #142, from August 1971:
A family of upper-class New Yorkers is heading to the Statue of Liberty to make the Hulk their latest "cause"; besides skewering liberal chic, this comic documents one of the silliest and shortest-lived fashion trends among the glitterati: the cartridge belt.
That's right, the woman in the second panel is not some sort of superhero, she's just fashion forward. You see, for about five minutes in the early seventies, everyone who was anyone in what we used to call the "jet set" had a gold- or silver-plated ammo belt slung over her shoulder. The whole idea was so stupid that even the world of haute couture rejected it almost immediately. I remember it. Don't believe me? Here's a copy of a photo from the New York Times of December 9, 1970:
Now, I had to find that photo in the NYT historical database from ProQuest, which I have access to only through my college, and I don't know how I would have found it unless I knew just what I was looking for (and about when). But right there on the pages of the Hulk comic is a remarkably similar image, documenting the same little ripple in fashion. Comics creators work in a context, and the work of the best will reflect the mores and minutiae of their time.
Comics: they're not just ripping yarns, they're little slices of history.