When Cheryl Shropshire learned that her son Atiba had dyslexia, a reading impairment, he was 6. He was placed in a private school for the learning disabled and quickly learned his alphabet and how to read.

"When I heard him putting sentences together, I was overjoyed," said Shropshire, 34, who lives in Northeast Washington.

But now, three years later, Atiba is still learning to put together sentences, and Shropshire said she is very concerned about her son's lack of progress.

She talked to her son's teachers and the administrators about her concerns, but little changed, she said.

Last weekend Shropshire was among 50 parents of handicapped children who attended a daylong workshop to learn from lawyers, psychologists and school administrators the rights of the handicapped and how to use the system to get the best education for their children.

Under a federal law adopted in 1975, local school systems must provide a free and appropriate education for all handicapped children between the ages of 2 and 21.

"The law says that your child should have all the necessary resources he may need to address his learning disabilities," said Jane Yohalem, staff attorney of the Mental Health Law Project, who spoke at the workshop held at Buchanan School on Capitol Hill. It was sponsored by Kennedy Institute Parenting Skills in Special Education Project and D.C. Parents of Learning Disabled Children.

Nancy Cohen, a lawyer specializing in the rights of the handicapped, urged the parents, whose children suffered from disabilities ranging from dyslexia to cerebral palsy and mental retardation, to "get involved from the very beginning to the very end."

"You have the right to appeal any placement, or any part of your child's special program. Your child's IEP Individualized Educational Program is the first step and the most important part of his program," she said.

"If your child needs daily therapy, but the school suggests only once a week because they don't have the resources," said Cohen, "then you don't have to accept this; they're required to find those resources outside the school."

In the District, about 6,700 handicapped students attend public schools. This includes 1,051 students enrolled in the District's eight special education schools and 5,000 who attend special classes in regular public schools.

The District pays to send 428 students, such as Atiba Shropshire, to classes at private institutions in the metropolitan area and around the country, said Doris Woodson, assistant superintendent for special education.

D.C. school board member Bob Boyd, chairman of the Committee on Specialized Educational Programs, who attended the workshop, said many of the complaints are valid and the system is trying to improve.

"People usually complain about whether or not their child has received the proper placement, or that we don't meet the 50-day deadline to place their child," said Boyd.

"The process is very complicated, and we have just started a Saturday service at the Child Study Center to process some of the children's placements that have been waiting."

"As long as I didn't understand my rights, they school teachers, specialists and others could tell me anything and I accepted it," Shropshire said after the workshop. "But not anymore. I plan on following through his program right down to the wire," she said.