Dorothy Rich, 77, an educator, author and lecturer who became one of the nation's best known and most persistent advocates for mobilizing parents' interest in their children's education, died of cancer on Sunday at her home in Washington. Parental involvement in the education of school-age children is largely taken for granted now. But it was not so when Rich was a teacher working in New York and Arlington County, Va., in the late 1950s and early 1960s. During her teacher training, the word "parent" was not even mentioned, she once said. But educational research in the 1960s and 1970s began to show a correlation between home life and students' success or failure, and Rich played a vital role in the movement to raise awareness among parents and students that learning happens before the school bell rings and after class is dismissed. As a columnist on school and home life for the Washington Post, she had the platform to draw attention to the issue.