CAMBRIDGE, Mass. (AP) _ A teacher was convicted Thursday of raping a 15-year-old student after luring him to her home and seducing him.

''I didn't do it 3/8 I didn't do it 3/8'' sobbed Karen Cross, 33, who was sentenced to three to five years in prison. She was carried from the courthouse on a stretcher.

Middlesex Superior Court Judge Robert Barton said Cross must serve at least one year in prison. The jury deliberated 16 hours before finding her guilty on one count of rape of child.

Prosecutors say Cross and the boy had sex three times in six weeks beginning on Valentine's Day in 1990. There were no allegations of physical force, but the boy wasn't legally old enough to consent to sex.

The boy, now 16, was then a sophomore at Tyngsboro Junior-Senior High School, in Tyngsboro, about 20 miles north of Boston. He was in a special class because of learning difficulties.

Barton also sentenced Cross to three years probation and ordered that she undergo psychiatric evaluation. He stayed the beginning of the sentence until Nov. 14 and allowed her to remain free pending an appeal.

Cross' attorney, James Dangora, had questioned the credibility of the boy, saying he changed his story several times while testifying last week.

Cross had said she only wanted to help the student, whom she described as moody and troubled.

Two jurors, Eric Hegdahl and the jury foreman, Barbara Bonfiglio, said the most convincing evidence against Cross were letters she admitted she had written to the teen-ager.

One letter said, ''I will love you always, even through the worst of times.''