Tristan Barrass, 13, died alongside his brother Blake, 14, at a house in the Shiregreen area of the city on Friday.
Heartbreaking footage has now emerged of the youngster on BBC series Our School.
He was filmed getting quizzed by teachers at class over his extravagant hairstyle.
Tristan told them: “My friend is dying of bone cancer, I asked if I could dye my hair yellow for him. His favourite colour is yellow.”
In another clip, Tristan is seen laughing with school friends during an assembly.
The documentary followed students and staff in secondary schools as students moved from Year 6 into Year 7.
Tristan’s mum Sarah Barrass and uncle Brandon Machin, 37 have been charged with murdering Tristan and Blake.
Barrass is also accused of three counts of attempted murder against two other children.
The pair were remanded in custody today and and will stand trial later in the year.
They appeared at Sheffield Crown Court this morning for a ten-minute hearing.
“My friend is dying of bone cancer, I asked if I could dye my hair yellow for him”
Emergency services had been scrambled to reports of concerns for safety at a house in Shiregreen on Friday morning.
A man and woman were then seen being arrested by police as tragic news emerged that two children had died.
The three-bed house the incident took place at sits just yards from a primary school where an air ambulance had to land as it helped with dramatic rescue efforts.
Tributes have been pictured being left outside the house by neighbours as the community reels from the events of Friday.