John "Jock" Denio was the driving force behind a successful new era at Brookside when he took over as headmaster in 1961.

A native of Massachusetts, Denio earned his Bachelor of Arts degree from Amherst College and his Master of Arts in education from Boston University. He also spent three years in the medical corps of the U.S. Air Force.

Denio was named as the replacement to Jessie Winter, who retired as headmistress after nearly 40 years of service at Brookside.

Denio was instrumental in carrying out the Cranbrook-Kingswood student teaching program at Brookside, in which seniors could work as teaching assistants in a semester credit course. He was also active in educational organizations—especially the Independent Association of the Central States—and served on numerous committees evaluating independent schools across the country.

Near the end of his career, Denio taught classes in cartography, cider making, orienteering and cardboard carpentry.

Denio initially estimated he would spend about 10 years at Brookside, but his career at the school lasted for more than 20 years. After his retirement in 1982, the Brookside library was dedicated in Denio’s name.