Beloved Brooklyn Math Teacher Remembered As Curious And Dedicated

BOERUM HILL, NY — Loved ones remembered late teacher Charl Castelyn as a loyal friend and dedicated educator who gave everything to his students.

Castelyn, a math teacher at Brooklyn's MS 447, "died peacefully at home" on Nov. 27 after a years-long battle with cancer that rallied the local community. Just a few days later, his loved ones honored him with a memorial service in Brooklyn.

"His absence will leave us with a hole in our hearts, but our memories of Charl will inspire us all," the veteran math teacher's loved ones said in his obituary.

"We remember Charl for his love of teaching, his sense of curiosity and adventure, his sincere kindness and warmth, his excellent sense of style, and his ever-present deadpan humor."

News of Castelyn's recent brain tumor affected the community greatly, his loved ones told Patch in October as his condition quickly worsened. He had already fought a rare type of cancer in 2012, and doctors subsequently found another mass in 2018.

In 2022, his cancer spread but Castelyn kept teaching — until his health took a quick turn for the worse this fall.

Word spread of Castelyn's troubles and his community quickly mobilized, raising over $60,800 to aid his recovery.

The support was "awe-inspiring," and speaks to the powerful impact Castelyn always had on his students, said his husband Craig Strulovitz and long-time friend and coworker Katherine Schrup.

Castelyn taught math in New York City schools for 19 years and had an incredible knack for changing kids' minds about a famously difficult subject, Schrup said.

His impact can be strongly felt in his students, most recently sixth-grade math students who jumped in to support their teacher after only knowing him a few months, Schrup said.

"He was passionate and successful in his work and found joy and comfort with his students and colleagues, even throughout the most challenging times of his life," his loved ones said in Castelyn's obituary.

Outside the classroom, Castelyn was adventurous, loved to travel, and made and kept friends easily with his warm personality. He deeply loved his dog, Odin, who sat in Castelyn's lap in his last moments.

"Charl made friends everywhere he went. He saw the good in everyone, and was endlessly loyal to his friends, with whom he managed to always keep in touch," his loved ones said in his obituary.