An 18-year-old student was arrested at a D.C. school yesterday for allegedly robbing a Metro passenger of an iPod, an expensive music-playing device that has become a pop-culture icon, a Metro spokesman said.

The electronic devices, which let people carry thousands of songs with them and listen to them through earphones, are about the size of a pack of cigarettes and have rapidly replaced the older portable Walkman-style stereos as the entertainment device of choice. Many people use them to alleviate the boredom of trips on crowded subway trains and the perceived tedium of many other activities.

Metro spokesman Steven Taubenkibel said the Nov. 10 iPod robbery, after which Beyanka Clark was arrested at Woodrow Wilson Senior High School, was the first such reported incident on the subway system.

But, he said, "it has been a problem in other subway systems" across the country. Earlier this year, the New York Times reported that authorities there had noted an increase in subway crime that included a substantial number of iPod thefts.

Taubenkibel said that a 27-year-old Northwest Washington woman was riding on a Red Line train near the Van Ness-UDC station about 4:30 p.m. Nov. 10 when a group of teenaged girls approached.

He said one of them snatched the rectangular metallic device and then another teenager blocked the victim from going after her. The devices commonly cost $200 to $300 or more.

While investigating the robbery, Taubenkibel said, authorities found that Clark had an iPod with her when she came to the attention of police Nov. 14 in connection with an unrelated matter. The nature of that matter could not be learned.

According to Taubenkibel, the iPod that was stolen bore a personalized inscription. Another Metro representative, Candace Smith, said Metro police were recommending that other iPod owners add similar markings as a possible aid to law enforcement.

Taubenkibel said last night that Metro was "advising our customers to keep valuables such as cell phones and iPods out of plain view."