This article explores the relationship between children's prior knowledge of spoken and written discourses and how this influences their attempts at examination writing. Particular emphasis is given to task demand in examination questions and how frequently this fails to acknowledge how prior knowledge might be realized in response to the question. School writing has specific genres of its own, genres which, although they may partially mirror genres found outside school, are nonetheless very specific. A significant factor in school genres is they emphasize an asymmetric power relationship between the teacher and the writer, with the teacher not only knowing the conventions of the genre, but often also acting as the determiner of the title, and as the arbiter of the finished piece of writing. Moreover, children whose home background has socioculturally prepared them for production of written genres are advantaged over those with different cultural and meaning-making resources available to them.