Writing Across the Curriculum looks at writing in different disciplines  from the twin perspectives of writing to learn and writing to communicate.

• "Writing to learn" is writing to oneself to discover, organize, understand, and learn some subject matter, and is usually short in length and unpolished. Thus, a variety of writing assignments, not just essays, can serve this purpose.
• "Writing to communicate" is writing to an audience to communicate one's understanding of some subject, thus typically taking on the form of a finished product.

For brief introductions to and examples on this topic, see:

• What is writing to learn? (The WAC Clearninghouse)
• Thinking Writing: News from the Writing in the Disciplines Initiative
• Examples of Writing to Learn Activities (The WAC Clearninghouse)

For how professors in different disciplines use and evaluate writing in their courses, see

• Examples from the Disciplines (U of Hawai'i at Manoa Writing Program)
• Department-by-Department Reference Guide (Marquette University)