The technology can be used in various ways: A quick question to the class to see if they understand; a full quiz of 20 or more questions; a sampling of opinion. Students simply push a button to send in their response. The results are presented in a graph on a monitor in front of the class so everybody can see.
In the program Henriques uses, the correct response is highlighted in green, so all the students can tell if they got it wrong, and how many others got it wrong, and thus how they stack up against the rest of the class.
It helps the students, but it also helps the professor.
"Sometimes it's very reassuring to see that they've gotten the message, and other times it's sobering to find out that they completely missed the point," Henriques says.
The "instant gratification," as he puts it, also underscores just how difficult it can be to overcome popularly held opinions that are just simply wrong.
Awhile back, Henriques gave a long lecture on schizophrenia, a buzz word that is often used in describing such things as a politician's ability to send very different messages to very different constituents.
A couple of days later he asked his students to define schizophrenia. Even though he had just stressed that it is not a multiple personality disorder, most of the students got it wrong.
"I was very deflated," he says.
The right answer?
"It is a split between one's thoughts, feelings and actions," he says.
The message was clear. Go back over it again.
Lee Dye's column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.