The family of a 15-year-old girl who was lit on fire at a Saskatoon high school has asked people to wear purple Tuesday when classes resume.

鈥淚t is her favourite colour,鈥� the girl鈥檚 grandmother said in an interview.

鈥淚t鈥檚 going to be a very long recovery, and we鈥檝e put it out there just to let her know that people are thinking of her and praying for her.鈥�

Students are to return to Evan Hardy Collegiate on Tuesday, where last week a witness said the girl had liquid from a black canister poured onto her head which was then lit on fire.

The witness said multiple teachers came out of a classroom to save her, using items of clothing to snuff out the flames.

Police have said the girl was in serious condition with burns after Thursday鈥檚 attack.

They also said a teacher who was hurt trying to put out the fire was sent to hospital.

The grandmother said the teen is in an Edmonton hospital but declined to provide details about her condition.

She said her granddaughter was at a Metallica concert with her family about a week before the attack. It鈥檚 one of her favourite bands.

鈥淧urple was just a colour that stood out for her,鈥� the grandmother said.

A 14-year-old girl, who was also a student at the school, is set to appear in court again Wednesday on charges of attempted murder, aggravated assault and arson.

Police have said a school resource officer took the accused into custody not long after the attack.

The accused and the victim cannot be identified under the Youth Criminal Justice Act.

Saskatoon Public Schools has said counselling supports have been made available to teachers and students at the high school, which has been closed for regular classes since Thursday.