This article explores the idea that in order to improve the way we teach children to write, we need to improve our understanding of children as writers. Although developing their metacognitive skills can give us a clearer window into children's understanding, we must be wary of assuming that they ascribe the same meaning to their metacognitive metalanguage as we, their teachers, do. But we also need to beware of making assessments based just on the children's writing -- children can use writing to hide from us what they do not know and cannot do. Through the presentation of three brief case studies of lower-attaining Year 4 (8-9-year-old boys) the article considers the implications of assessing writing without acknowledging the role of the writer.