Gill Bremner, head of Wilmslow High School, where Hannah Thomas-Jones was a Year 9 student, said she would be "sadly missed" by pupils and teachers.
She said: "Hannah's death is a very sad loss for this school. Our sympathies go out to her family at this time after such a tragic incident."
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The annual event has earned a place in the record books ahead of the grand final of the 60th anniversary show in Austria this evening.
Local authorities said the move is necessary to "avert the growing number of deaths and increasing harm linked to psychoactive substances".
Some students argued that the centuries-old tradition of wearing gowns, suits and mortarboards to exams was 'archaic' and looked elitist.