Kathleen answers the big question to win
She was the unanimous choice of the judges: Ewan Aitken, Cosla's education spokesperson; Neil Munro, editor of The TESS; and Gillian Macdonald, assistant editor.
Her winning entry, for which she will receive pound;200, will be published next week. The school's English department, which submitted her essay, will also receive pound;200.
Councillor Aitken, who conceived the idea for the competition in his regular TESS column last November, said it was important to engage the thinking of young people in what is "the next big question that will shape our world and the society we live in" - planning for life after oil.
Kathleen, the panel agreed, presented her arguments well from an arresting beginning: "In the time it takes you to read this sentence, 600 tonnes of oil will have been used."