Facebook recently tested a new feature: “satire” tags that warn gullible readers when a news story or web site is a joke. I sincerely hope none of my former students needs to rely on it. In fact, though I’m not sure what this says about me, two of my all-time favorite teaching resources are hoaxes.

The first is an essay called “Body Ritual among the Nacirema.” An anthropological study of the exotic Nacirema people, the paper expresses both wonder and disgust at customs such as “inserting a small bundle of hog hairs into the mouth, along with certain magical powders, and then moving the bundle in a highly formalized series of gestures.” With women who bake their heads in small ovens and men who ritually lacerate their faces each morning, the Nacirema—spell that backward—are a strange tribe indeed.

The second resource purports to be the work of researchers studying a dangerous substance called dihydrogen monoxide (DHMO). The site, which never mentions that DHMO is more commonly known as water, calls for concerned citizens to join in a public awareness campaign targeting the chemical and those who use it. Its claims are alarming, its pleas urgent. Some of the content is baldly fictitious, but some is irrefutable: surely DHMO is “a major component of acid rain and an important cause of erosion,” and no doubt dairy farmers urge cows “to ingest large quantities of DHMO, with studies showing that this practice can lead to increased milk production.”

Each of these readings can play a number of powerful roles in the classroom. For example, I sometimes ask students, totally out of the blue, to decide whether a substance called dihydrogen monoxide should be banned. Usually one or two—experts in either chemistry or Internet searches—say no almost immediately. Most, however, click on the first link Google gives them: the prank site. Of these, a few are suspicious enough of its flashing clickbait and silly advertisements to perform a thorough background check on the supposed authors, but many get straight to work taking notes on the manifold evils of DHMO. When it comes to teaching research skills, the activity is both a diagnostic tool and a learning experience in itself.

We often Challenge students to do more: work harder, think further, try longer. That is as it should be. What I like about these hoaxes, though, is that they pose an even more daunting Challenge: they demand not something more but something different. Just as importantly, they prompt students to Challenge themselves and others. Beginning a research project with a lesson on DHMO? Be prepared to field complaints from students who can’t find sources credible enough for their taste. Using the Nacirema to introduce a work of literature set in a faraway place or time? Expect heated discussions about who is and is not judging the characters’ culture unjustly. It sounds too pat, but I think it’s true: Challenging students, at its best, means being Challenged by them.