Leo C. Bennett, 70, a teacher and principal in Prince George's County elementary schools for more than 25 years, died of congestive heart failure Wednesday in a Harrisburg, Pa., hospital.

She joined the Prince George's County schools as a science teacher at Capitol Heights Elementary School in 1942. Three years later she moved to Bowie Elementary where she became principal. She then served as principal of West Lanham Hills Elementary School for 1953 until retiring 16 years later.

Mrs. Bennett received a national science award from the Izaak Walton League during the 1960s for outdoor education for the raccoon nature trail she helped run at West Lanham Hills.

She was a native of Webster Springs, W.Va. She attended colleges in West Virginia, George Washington University, and graduated from the University of Maryland.

She taught school in West Virginia before moving here.

She was the widow of Fred J. Bennett, a former principal at Bowie Elementary School, who died in 1947.

Mrs. Bennett maintained a home in Hyattsville, but had lived with her son, Dr. John Bennett, in Harrisburg for the past three years.

In addition to her son, she is survived by a brother, King Cogar, of Charleston, W.Va.; a sister, Madelyn Barnett, of Fairfield, Conn., and four grandchildren.