U.S. teenagers think they are savvy about cybersecurity — so much that nearly one-third skirt school safeguards to access banned content and 29 percent admit to using tech devices to cheat in school — but more than twice that many say they know of classmates who have cheated with devices, a survey found.

The findings of the survey by the computer security firm McAfee are in proportion with a 2009 survey by Common Sense Media — although the exact extent of cheating, and whether it’s changed over the years, is unknown.

It’s easy, students said, to take a cellphone photo of notes or test answers, and then peek at it surreptitiously while taking a test. At the same time, they note, vigilant teachers notice those wayward glances.

McAfee conducted the online survey in June of about 3,902 high school students ages 14 to 18 years old — 1,201 of them in the United States, the rest in Australia, Canada and the United Kingdom. In general, the percentages of reported cheating and accessing banned sites were higher in the U.S.

So was the percentage of teenagers who reported being cyberbullied: 30 percent in the U.S., compared with 22 percent in the survey overall. Of the U.S. students who said they had been victimized, half of those reported incidents before starting high school.

Those figures are disheartening, considering the effort put into raising awareness of cyberbullying and combating it, said Gary Davis of McAfee. He suggested educating children starting at an early age to help them stay safe online. “They need to understand what they should do to not be a victim.”

Some teenagers said the survey may understate the prevalence of cyberbullying. “It does surprise me, I’d expect it to be higher,” said Julia Kolman, 16, a rising senior at Branham High School in San Jose, Calif. “A lot of people take to Twitter to create fake accounts or use personal accounts to harass other students.”

Among the platforms that the survey indicated are most used for cyberbullying among U.S. teenagers, Facebook appeared at the top with 71 percent, followed by Instagram with 62 percent and Snapchat with 49 percent.

More than 70 percent of U.S. teenagers surveyed said they would feel comfortable talking with an adult at school if they were cyberbullied, the survey reported. Fewer than half of the teenagers surveyed — 44 percent — said they receive regular online guidance from school, and 46 percent said their parents talk to them about staying safe, although the percentage diminishes to 33 percent with 16 to 18 year olds. Of the older group, 14 percent said they have never had an online safety talk with their parents.