Shane McGregor, who was head of English at St Patrick’s College in Maghera, died suddenly on Saturday.
The popular teacher, who lived in Draperstown, taught at St Patrick’s College for a number of years.
School principal Katrina Crilly posted an emotional tribute to her former colleague on social media.
“We are absolutely devastated @StPatsMaghera to lose Shane,” she wrote.
“We started on the same day and had the best of craic for many years.
“I returned to work alongside him again only to be cut so short.”
Ms Crilly said Mr McGregor was highly thought of.
“He will be sorely missed by students who adored him and staff,” she added.
Earlier the popular south Derry school had said on social media it learned of Mr McGregor’s death with “deep regret” and described him as an “esteemed colleague and friend”.
The school offered its condolences to Mr McGregor’s family adding “we are heartbroken”.
Gemma Brolly, Aontú representative and deputy leader, offered her condolences.
“As a teacher myself I know the heart we put in and he obviously was a great example of what it is to be a teacher,” she said.