Ines Alves, a pupil at Sacred Heart school in Hammersmith, London, even took her revision notes with her as she escaped from the block of flats on Tuesday 13 June.
‘This Morning’ host Eamonn Holmes told Alves she was “absolutely incredible” for going into school the next day at 9am to sit her exam.
“I want to take chemistry for A Level and needed to get a good grade in my science GCSE to go ahead,” she explained on the ITV show on Friday 16 June.
“It’s my strongest science, it was worth doing it [rather] than not doing it.”
When asked if it was hard sitting the exam, considering what had happened the night before, Alves said: “It was always there on my mind, but it was a way of escaping it and not thinking about it.
“My school and friends were really supportive. My friends brought in clothes and toiletries - everything I would need - and gave me money as well.”
Alves appeared on the show with her brother, Tiago, 20, who said their family didn’t put any pressure on her to go to school.
“I really do not have words to describe what she did,” he said.
“At the time I said you don’t have to go in, but she persevered and said she wanted to go and do it.
“She’s been revising and making her chemistry notes and I knew she wanted to do this.”
Alves and her family were in their flat on the 13th floor when their dad noticed the fire in its early stages after coming back from dinner with his wife.
The family are now staying with friends until the council arrange longer-term accommodation.
‘This Morning’ is on ITV on weekdays from 10.30am.