WHEATON, Md. (AP) _ A high school dropout who saw two of her sons quit school as teen-agers has graduated from college with straight A's.

Janet Johnson, 43, of Wheaton, earned a perfect 4.0 grade average and was valedictorian at Tuesday's commencement for the School of Education at the University of Maryland.

''I can't come down yet. It's the highest point of my life so far,'' she said Wednesday.

She had quit high school at age 16 to get married and have a family. Years later, she earned a high school equivalency degree.

Mrs. Johnson had worked as a teacher's aide and secretary before deciding it wasn't too late to try for a college degree in elementary education. She received an associate's degree after attending night classes at Montgomery College in Rockville for three years.

''When I went to the University of Maryland, I won a $5,000 scholarship and all these wonderful things started happening,'' she said. ''It's been fabulous.''

In her graduation address, she thanked her fellow students for including her in activities and treating her as one of them.

''They'd say, 'Come on, Janet, we're going to have something to eat together.' They wanted me to go. That felt good. They didn't make me feel different.''

Her two older children, ages 25 and 26, dropped out of high school but also received high school equivalency degrees. Her third son is 15. Her husband retired with a disability after working as a firefighter. She also has a young grandchild.

''It was a struggle without my income for the past two years, but we said, 'We can do it' and we did,'' she said. ''It was hard especially with the family. There were things I couldn't do for the children that I wanted to.''

Mrs. Johnson hopes her scholastic success will motivate her youngest son to try harder in school.

''It did seem to have an effect on him. I really want him to continue his education,'' she said.

Mrs. Johnson has a contract with the Montgomery County school system to teach in an elementary school this fall. She is now working as a substitute teacher at Head Start.

''I put a lot of effort into it, and worked a little harder,'' she said. ''Being a little bit older and just living, you learn. And I didn't have to worry about toga parties and sororities.''