If a 42-year-old Florida teacher is convicted of having an 18-month relationship with a 14-year-old, she won't be the first female teacher in the nation to have become illegally involved with a student.

Cases such as Beth Friedman's, in which the teacher allegedly gave gifts to a student she met in her study skills class to encourage a sexual relationship, have popped up across the country in recent years.

The biggest name in teacher-student sex cases is Mary Kay Letourneau, the 36-year-old teacher from Washington State whose affair with a 13-year-old student got her national media coverage, two children and a prison term.

Letourneau first made headlines in 1996 for admitting to a relationship with her 13-year-old student, Vili Fualaau. Letourneau, who was married and had children, pleaded guilty to statutory rape and received a seven-and-a-half year suspended prison sentence.

But Letourneau didn't stop seeing Fualaau and became pregnant by the boy a second time while out of prison. This prompted a judge to send her to jail to serve the remainder of her sentence.

Female sex offenders are rare compared with male sex offenders, representing an estimated 10 percent of sex offenders, according to sex abuse experts. In Florida, they represent approximately one percent of registered sex offenders.

Another case concerned a middle school teacher with three children who was charged with three counts of lewd, lascivious or indecent assault or act on a child.

Denise McBryde, a 38-year-old Florida teacher was accused in 1998 of having a relationship with a 15-year-old student.

McBryde met the youth at Florida College Academy and admitted to having sexual relations with him at her home, the teen's home and a hotel.

In another case, Minnesota high-school teacher Julie Feil, 32, pleaded guilty in 1998 to having a three-month sexual relationship with a 15-year-old boy in her English class.

"I loved him the best way I knew how," Feil said at her sentencing. In some cases, although the students are minors, the teachers themselves are barely adults.

Two Carroll County, Minn., teachers were recently charged with having sex with boys between 15 and 17 years of age.

Kimberly Merson, 24, a substitute teacher and cheerleading coach at Francis Scott Key Hight School, was charged with inappropriate sexual conduct after she allegedly got eight boys between 15 and 17 drunk, brought them to her home, stripped for them and had sex with them. Merson, who pleaded guilty in July, is scheduled to be sentenced in September

Tracie Mokry, 21, a student teacher in the art department, was charged with bringing seven male students to a weekend party where she drank with them and had sex with a 16-year-old and a 17-year-old. The charges against her were eventually dropped.