Grace S. McKenna, 85, a D.C. public school teacher for 48 years before her retirement in 1965, died of a stroke Saturday at Suburban Hospital in Bethesda.

A native of Buffalo, N.Y., Mrs. McKenna graduated from old Wilson Teachers College here. She began her career in 1917 at Langdon Elementary School and started teaching sixth grade in 1928. In 1931, she transferred to Lafayette Elementary, where she spent the remainder of her career.

At her retirement reception, attended by more than 600 friends, colleagues and former pupils, and reported in The Washington Post, one former student told of how Mrs. McKenna, who had been her teacher during World War II, made her class map theaters of operation, solve logistical problems and interpret strategy. "She made us stretch to the utmost powers we never knew we had," she said.

Another student, who was in Mrs. McKenna's last sixth-grade class, summed up her feelings about her teacher this way: "I do not think of you as an ordinary teacher. . . Sometimes on Monday mornings when i didn't particularly want to come to school, I felt pretty bad about the whole thing. But then when I came into our classroom, I felt much better because there was such a nice feeling in there."

Mrs. McKenna, who lived in Bethesda, was active in the Sanctuary Sodality and in the Second and Fourth Monday Club at the Shrine of the Most Blessed Sacrament Catholic Church here.

She was the widow of Harry P. McKenna, a Washington attorney, who died in 1932.

Survivors include a son, Gerald S. of Bethesda; two daughters, Patricia Halpin of Great Falls, Va., and Sister Judith, C.S.C., of Washington, and 15 grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to SOME Inc. (So Others May Eat) in Washington.