It’s nothing to LOL about: Despite best efforts to keep school writing assignments formal, two-thirds of teens admit in a survey that emoticons and other informal styles have crept in.

The Pew Internet and American Life Project, in a study released yesterday, also found that teens who keep Web blogs or use social-networking sites like Facebook or News Corp.’s MySpace have a greater tendency to slip nonstandard elements into assignments. The results may give parents, teachers and others a big 🙁 — a frown to the rest of us — though the study’s authors see hope.

“It’s a teachable moment,” a senior research specialist at Pew, Amanda Lenhart, said. “If you find that in a child’s or student’s writing, that’s an opportunity to address the differences between formal and informal writing. They learn to make the distinction … just as they learn not to use slang terms in formal writing.”

Half of the teens surveyed say they sometimes fail to use proper capitalization and punctuation in assignments, while 38% have carried over the shortcuts typical in instant messaging or e-mail messages, such as “LOL” for “laughing out loud.” A quarter of teens have used 🙂 and other emoticons.

Overall, 64% have used at least one of the informal elements in school. Teens who consider electronic communications with friends as “writing” are more likely to carry the informal elements into school assignments than those who distinguish the two. The study was co-sponsored by the National Commission on Writing at the College Board, the nonprofit group that administers the SAT and other placement tests.

The chairman of the commission’s advisory board, Richard Sterling, said the rules could possibly change completely within a generation or two: Perhaps the start of sentences would no longer need capitalization, the way the use of commas has decreased over the past few decades. “Language changes,” Sterling said.

Defying conventional wisdom, the study also found that the generation born digital is shunning computer use for most assignments. About two-thirds of teens say they typically do their school writing by hand. And for personal writing outside school, longhand is even more popular — the preferred form for nearly three-quarters of teens.

That could be because the majority of writing is short — school assignments are on average a paragraph to a page in length, Ms. Lenhart said.