Theodore R. Sizer, former dean of the Harvard Graduate School of Education and innovative educational reformer, died last week of colon cancer at his Harvard, Mass., home at the age of 77.

Sizer, who was known as the “boy dean” on campus after being selected as Dean of the GSE at the age of 31, had to grapple with the societal upheaval of the 1960s during his term, including the Vietnam War and student riots, according to Patricia A. Graham, a professor of the history of American education and another former dean of the GSE.

During the 1969 campus riots, Graham said Sizer served as a mediator between students and University administrators, because “he was the youngest dean, and administration thought that he could best relate to the rioters.”

Although Sizer had a “baptism under fire,” he had “the temperament to lead,” according to his close friend and former GSE Associate Dean Arthur G. Powell.

“Even people who disagreed with his ideas respected him as a person...which was not an automatic thing,” Powell said.

Powell added that Sizer wanted to focus education around the culture that children grew up in instead of just directing all attention to what happened in school. He recalled a day when Sesame Street characters Big Bird, Bert, and Ernie put on a show in the Science Center after research by a colleague on early childhood education that Sizer had promoted.

“There was never a happier moment in a decade that was difficult,” Powell said.

Sizer graduated from Yale with a degree in English in 1953, and went on to serve in the Army and to work as a high school teacher. He then received his A.M. and Ph.D. from the GSE.

Shortly thereafter, then-University President Nathan M. Pusey ’28 named him GSE Dean in 1964. Sizer left Harvard in 1972 to become the headmaster at Philips Academy Andover, and in 1994 was named Department Head for Education and Director of the Annenberg Institute for School Reform at Brown University.

In 1984, he collected his thoughts on education in his book “Horace’s Compromise,” which Powell said helped Sizer “find his voice” and served as inspiration for the Coalition of Essential Schools, which emphasizes the role of students as workers and of teachers as coaches.

In an e-mailed statement, Sizer’s close friend Professor Howard E. Gardner ’65, wrote that, “in our time Ted Sizer was the pre-eminent proponent and spokesperson for progressive education, the one form of education that is distinctly American.”