EXETER - John Charles Warren, 87, died Sunday, June 24, 2012, at the Monadnock Lodge at RiverWoods in Exeter. He was born Feb. 25, 1925, in Orange, Mass., the son of Howard P. and Arlene W. Warren. He was raised in Orange, where his father was an active civic leader and businessman. He was a U.S. Navy veteran of World War II, serving as a pilot. He attended Williams College, where he majored in art history and was a varsity swimmer. He completed graduate study in the teaching of mathematics at Columbia University and the University of New Hampshire. Mr. Warren was a life-long teacher of high school mathematics, beginning his career at St. Johnsbury Academy in St. Johnsbury, Vt., in 1950. In 1955, he moved to Exeter to join the faculty of Phillips Exeter Academy, where he taught for 30 years. He was a gifted teacher known for a patient and gentle demeanor that guided thousands of students to a deeper knowledge and appreciation of mathematics. He was equally involved in student life outside of the classroom, in the dormitory and in sports. He was a crew coach, teaching new oarsmen the basics of the sport. On most days on the water, he preferred to coach from a single scull he rowed himself, and not from the traditional motor launch. He felt it was more effective to demonstrate proper technique when he was holding his own oar. He served for many years as the academy's official photographer. In 1963, he took a sabbatical from the academy to study computer science at Dartmouth College in a new program exploring the potential of introducing computers into the teaching of mathematics. When he returned to Phillips Exeter the following year, he established a computer time-sharing program with Dartmouth, making Exeter the first high-school computer program in the country. In 1985, he left Phillips Exeter to teach math at Burke Mountain Academy in northern Vermont. He loved to ski and Burke was a ski academy that produced many U.S. Olympians. He and his wife, Nancy, retired to Vermont, where he continued to ski and enjoy the outdoors. He joined the Nature Conservancy and became an active steward in the conservancy's loon preservation program in the northern Vermont lakes. He and Nancy moved to RiverWoods in Exeter in 2003. He is survived by his wife, Nancy; four sons, David of London, England, Peter of South Freeport, Maine, William of Coconut Grove, Fla., and Michael of Dover, Mass.; one daughter, Ann, of Cape Elizabeth, Maine; and five grandchildren. At Mr. Warren's request, the family will not be holding any memorial services. The family suggests memorial donations may be made to the Spencer Scholarship Fund for the training of nurses at RiverWoods in Exeter, or to a charity of your choice, and that any donation be made anonymously.