EVANSTON, Ill. >> If any of the 70 undergraduates in Bill White’s course “Organizational Behavior” here at Northwestern University are late for class, or not paying attention, he will know without having to scan the lecture hall.

Their “clickers” will tell him.

Every student in White’s class has been assigned a palm-sized, wireless device that looks like a TV remote but has a far less entertaining purpose. With their clickers in hand, the students in White’s class automatically clock in as “present” as they walk into class.

They then use the numbered buttons on the devices to answer multiple-choice quizzes that count for nearly 20 percent of their grade, and that always begin precisely one minute into class. Later, with a click, they can signal to their teacher without raising a hand that they are confused by the day’s lesson.

But the greatest impact of such devices — which more than a half-million students are using this fall on several thousand college campuses — may be cultural: They have altered, perhaps irrevocably, the nap schedules of anyone who might have hoped to catch a few winks in the back row, and made it harder for them to respond to text messages, e-mail and other distractions.

In White’s 90-minute class, as in similar classes at Harvard, the University of Arizona and Vanderbilt, barely 15 minutes pass without his asking students to “grab your clickers” to provide feedback

Though some Northwestern students say they resent the potential Big Brother aspect of all this, Jasmine Morris, a senior majoring in industrial engineering, is not one of them.

“I actually kind of like it,” Morris said after a class last week. “It does make you read. It makes you pay attention. It reinforces what you’re supposed to be doing as a student.”

Inevitably, some students have been tempted to see clickers as “cat and mouse” game pieces. Noshir Contractor, who teaches a class on social networking to Northwestern undergraduates, said he began using clickers in spring 2008 — and, not long after, watched a student array perhaps five of the devices in front of him.

The owners had skipped class, but their clickers had made it.

Contractor said he tipped his cap to the students’ creativity — this was, after all, a class on social networking — but then reminded them that there “are other ways to count attendance,” and that, by the way, they were all signatories to the school’s honor principle. The practice stopped, he said.

Though the technology is relatively new, preliminary studies at Harvard and Ohio State, among other institutions, suggest that engaging students in class through a device as familiar to them as a cell phone — there are even applications that convert iPads and BlackBerries into class-ready clickers — increases their understanding of material that may otherwise be conveyed in traditional lectures.

The clickers are also gaining wide use in middle and high schools, as well as at corporate gatherings. Whatever the setting, audience responses are received on a computer at the front of the room and instantly translated into colorful bar graphs displayed on a giant monitor.

The remotes used at Northwestern were made by Turning Technologies, a company in Youngstown, Ohio, and are compatible with PowerPoint. Depending on the model, the hand-helds can sell for $30 to $70 each. Some colleges require students to buy them; others lend them to students.

Tina Rooks, the chief instructional officer for Turning Technologies, said the company expected to ship more than 1 million clickers this year, with roughly half destined for about 2,500 university campuses, including community colleges and for-profit institutions. The company said its higher-education sales had grown 60 percent since 2008, and 95 percent since 2006.

At Northwestern, more than three dozen professors now use clickers in their classrooms. White, who teaches industrial engineering, was among the first here to adopt them about six years ago.

He smiled knowingly when asked about some students’ professed dislike of the clickers.

“They should walk in with them in their hands, on time, ready to go,” he said.

White acknowledged, though, that the clickers were hardly a silver bullet for engaging students, and that they were just one of many tools he employed, including video clips, guest speakers and calling on individual students to share their thoughts.

“Everyone learns differently,” he said. “Some learn watching stuff. Some learn by listening. Some learn by reading. I try to mix it all into every class.”

Many of White’s students said the highlight of his class was often the display of results of a survey-via-clicker, when they could see whether their classmates shared their opinions. They also said that they appreciated the anonymity, and that while the professor might know how they responded, their peers would not.

Last week, for example, he flashed a photo of the university president, Morton Schapiro, onto the screen, along with a question, “Source of power?” followed by these possible answers:

— 1. Coercive power (sometimes punitive).

— 2. Reward power.

— 3. Legitimate power (typically by virtue of one’s office).

— 4. Expert power (more typically applied to someone like an electrician or a mechanic).

— 5. Referent power (usually tied to how the leader is viewed personally).

To White’s seeming relief, a clear majority, 71 percent, chose No. 3, a sign that they considered his ultimate boss to be “legitimate.”

And then, to his delight, the students emerged from their electronic veils to register their opinions the old-fashioned way.

“They can be very reluctant to speak when they think they’re in the minority,” he said. “Once they see they’re not the only ones, they speak up more.”

© 2010 The New York Times Company