Banning baseball caps during tests was obvious — students were writing the answers under the brim. Then, schools started banning cellphones, realizing students could text message the answers to each other. Now, schools are taking aim at digital media players as potential cheating devices.

Devices including iPods and Zunes can be hidden under clothing, with just an earbud and a wire snaking behind an ear and into a shirt collar to give them away, according to school officials.

"It doesn't take long to get out of the loop with teenagers," said Aaron Maybon, principal of Mountain View High School in Meridian, Idaho. "They come up with new and creative ways to cheat pretty fast."

Shana Kemp, spokeswoman for the U.S. National Association of Secondary School Principals, said she does not have hard statistics on the phenomenon, but added it is not unusual for schools to ban digital media players. "We hope that each district will have a policy in place for technology — it keeps a lot of the problems down."

Mountain View recently enacted a ban on digital media players after school officials realized some students were downloading formulas and other material onto the players.

Schools in Seattle have banned the devices. St. Mary's College, a high school in Sault Ste. Marie, Ont., banned cellphones and digital media players this year, while the University of Tasmania in Australia prohibits iPods, electronic dictionaries, CD players and spellchecking devices.

Sneaky new ways to cheat

Using the devices to cheat is hardly new, Kemp said. However, sometimes it takes awhile for teachers and administrators, who come from an older generation, to catch on to the various ways the technology can be used.

Some students use iPod-compatible voice recorders to record test answers in advance and them play them back, said 16-year-old Mountain View junior Damir Bazdar. Others download crib notes onto the music players and hide them in the "lyrics" text files.

Kelsey Nelson, a 17-year-old senior at the school, said she used to listen to music after completing her tests — something she can no longer do since the ban. Still, she said, the ban has not stopped some students from using the devices.

"You can just thread the earbud up your sleeve and then hold it to your ear like you're resting your head on your hand," Nelson said.

Schools around the world are hoping bans will at least stave off some cheaters. Conversely, Duke University in North Carolina began providing iPods to its students three years ago as part of an experiment to see how the devices could be used to enhance learning.

The music players proved to be invaluable for some courses, including music, engineering and sociology classes, said Tim Dodd, executive director of the Center for Academic Integrity at Duke. At Duke, incidents of cheating have declined over the past 10 years, largely because the community expects its students to have academic integrity, he said.

"Trying to fight the technology without a dialogue on values and expectations is a losing battle," Dodd said. "I think there's kind of a backdoor benefit here. As teachers are thinking about how technology has corrupted, they're also thinking about ways it can be used productively."