The poster on the math teacher's door said, "3 out of 2 people have trouble with fractions."
It was an example of that light-hearted approach that Bruce McCallum brought to math class, as he helped students work through what many of them saw as their toughest subject.
The poster, comic books and travel photographs were carefully set out for a memorial next to a photo of the 59-year-old Albert Campbell Collegiate Institute teacher.
McCallum was stabbed Sunday while vacationing in the coastal tourist town of Puerto Viejo, Costa Rica.
Diliana Pazin's eyes were heavy and tired as she signed the book of condolence, though the school's guidance counsellor smiled as she remembered her colleague.
"Bruce would always walk with a smile on his face. No matter what. He was felt in the school, I guess, students would say 'one of the cool teachers.'"
The math teacher spent 18 of his 20 years at the high school in suburban Scarborough.
"He really made a difference in kids' lives and we lost a colleague, we lost a family member," Pazin said.
His colleague, Caroline Crabtree, is also in the math department and said her friend and colleague was exceptional with "a calling" to teach.
She said it was McCallum's second career. He attended high school in Hamilton at the general/applied level and with a dream to teach, went back to school later in life.
His roots as a student in general classes inspired his approach when he taught, "especially with those who are applied," Crabtree said.
She said he had a gift with "the kids who had a difficult time with math by creating an environment where math class was safe where you could come where you weren't judged."
Grade 12 student Jeremy Tsang remembered the first moment he met McCallum. Tsang had been waiting for remedial help with grade 10 linear systems and his math teacher, not McCallum, had forgotten about their meeting. McCallum walked into the room and immediately stepped in to help.
Tsang was in McCallum's math class the following year.
Fighting back tears, the 17-year-old said, "I had an awesome time in Mr. McCallum's class ... the class used to laugh, I asked lots of questions. Students got to interact with him. He was amazing."
Police said the 59-year-old was attacked as he went out to take photographs of the sunrise. Local police told CBC Toronto on Wednesday that video footage from the scene showed two teenagers confront McCallum before dawn.
"They kicked out at the camera and when he tried to fight back, they took out a knife," said Rafael Arajna, speaking for the Costa Rican police agency Seguridad Publica.
The attackers stole McCallum's camera and left him lying on the road, according to Arajna, who added that a third person may have been involved.
No arrests have been made.
'Caring and dedicated'
It's unclear how long McCallum had been in Costa Rica. He was travelling the world on a year-long sabbatical that began in New Zealand and Australia.
"He was a caring and dedicated member of our teaching team [and] was a positive role model in the Campbell community who had a passion for photography and travel," school principal Carol Richards-Sauer wrote in a letter to students Wednesday. "His energy and work ethic were an inspiration to us all."
McCallum was involved in extra-curricular activities at the school. He ran a comics and anime club, and supervised the archery team.
Global Affairs Canada told CBC Toronto that consular officials are working with Costa Rican authorities and providing assistance to McCallum's family.