In this study, we explored how students make use of whole-class interaction in individual writing. Although various studies show the importance of classroom interaction for writing, little is known about how this works, particularly in history. Starting point is the idea that learning can move from the interpersonal level in classroom discourse to the intrapersonal level in subsequent individual writing. We analyzed nine student texts in history (Grade 11) and traced back the origins of the ideas used (documents or discussion). We found that students not only referenced both documents and classroom discussion in their texts but also that they developed additional ideas. We identified two ways in which students used classroom interaction in their texts: reproducing existing ideas or transforming existing ideas into new ones. Examples of both are discussed. Furthermore, we found differences in students' use of the language of history in the discussion and in writing. When writing, students seemed to use more nominalizations and the language of time was more complex. We conclude that individual writing can benefit from whole-class discussion because students reproduced and transformed ideas in their writing, resulting in knowledge development, and because students' use of the language of history became more proficient.