Kathy Witcher knew her student's paper on "Huckleberry Finn" sounded too mature for an 11th-grader.

"The light was society," the student wrote. "And Huck lived on the lampshade."

The Plano, Texas, English teacher put her suspicions to the test and searched for the phrase on the Internet. The idea behind the metaphor popped up.

"When they write for us, it's like a fingerprint," said Witcher, who gave the Plano East Senior High School student a zero. "They don't change from mediocre writers to great writers overnight."

Score one for the teachers in an intensifying war on plagiarism.

Cheating is as old as homework, but educators say plagiarism appears to be more rampant than ever in high schools and at colleges and universities. They blame the Internet. Students among the first generation to grow up online are writing term papers with unlimited resources at their fingertips, rather than combing the shelves at the library.

But these young people, educators say, often don't understand that surfing Web sites and lifting passages for their own assignments is stealing ideas, thoughts and words from others.

"Students use it like an 8-billion-page, cut-and-pasteable encyclopedia," said John Barrie, who created a Web site www.turnitin.com, which exposes plagiarized work.

Educators are employing various tactics to fight the problem. Some schools sign on to the Internet themselves to catch cheaters. Others are writing honor codes packed with clear rules about plagiarism and a menu of penalties.

National student surveys run by the Center for Academic Integrity reveal the trend. In 1999, 10 percent of college students anonymously admitted to plagiarizing sources from the Internet, according to the center, which surveyed 50,000 undergraduates at 60 institutions. Last year, 40 percent admitted doing so.

In a nationwide survey of 18,000 high school students from 61 campuses, 60 percent admitted to some form of plagiarism, according to the center.

"There are more means available to cheat," said Tim Dodd, executive director of the Center for Academic Integrity at Duke University's Kenan Institute for Ethics. "But an ethical person, regardless of the variety of means, is not going to use them."

High school and college educators say they don't need surveys to prove the point.

"Every year, the kids are a little lazier than the kids before," Diane Hamilton, an English teacher at Martin High School in Arlington, Texas, said. "Is it all the Internet? No, but that's part of it. Within 15 minutes, they get all they need, and their work ethic just isn't that good anymore."

Kimberly Harris, a college music professor, said she sees plagiarized work every year.

"To find plagiarism every semester to me means it's prevalent," said Harris, a Collin County Community College instructor.

Harris, who has been teaching for 11 years, reported four cases to the dean's office last year, the most she's ever had in one term. After three students in her online course were challenged, they dropped the class.

"That's what happens a lot of times as soon as the dean's office calls them on it," she said.

The fourth denied cheating, but lost his case in a hearing with administrators, she said. He flunked the course.

"If I give someone an F, is it going to ruin his life? No," Harris said. "But I want them to know that in life there are consequences."

Some who plagiarize buy papers online, though more students copy and paste information into reports and pass it off as their own.

"Many of the students have a philosophy that as long as they're not hurting anyone else, then it's fine, but we have to explain to them that there are rules on that," said Stacey Raymer, who teaches English at Rowlett High School.

Some students believe gathering information online and using it as their own without citing sources is legitimate.

Other students think paraphrasing without a citation is OK, too. But it's not.

"They think if they don't state the same thing exactly the way an author states it, change a few words here and there, that it's not plagiarism," Barbara Lusk, faculty association president at Collin County Community College, said.

High school instructors go over the rules with students, but they often go misunderstood.

Michelle Lee, a Frisco High School senior, said she's careful about checking her sources in papers, but she knows many students don't understand the importance.

"When it comes to plagiarism," she said, "it's not black and white."

Some students know fully well that they're breaking the rules, educators say.

Students give into temptations to cheat under pressures to succeed, Dodd, of the Center for Academic Integrity, said. High school students aiming for college are expected to participate in various extracurricular activities while maintaining good grades. College students headed for graduate schools face the same pressures. Scholarships are won and lost based in part on grade-point averages.

"There is extraordinary societal pressure to do well," Dodd said. "The gentleman's C is not part of the discourse anymore. Everyone has to be an A and B student.

"In many institutions, students are busier than they've ever been," Dodd said. "They're working, they've got school and extracurricular activities. Most of the time, they're in a time crunch."

Educators refuse to give up the fight.

High schools and colleges have long had rules against cheating, but now some have written honor codes and convened committees of students and administrators who spread the word about consequences. Some institutions subscribe to Web sites designed to detect copied work, while others employ Internet search engines for the same purpose.

Punishment at colleges and universities ranges from an "F" on a paper or in a course to suspension or expulsion. Chronic offenders face the stiffest penalties.