The majority of people, mathematicians included, think that writing out formulas is exactly what we call writing in math-ematics. I was guilty of the same preconceptions before I started to work with the Writing Across the Curriculum Project at Medgar Evers College (WAC @ MEC). The definition of writ-ing to learn that we use at MEC helped me come up with the idea that served as the basic principle for my further experi-ments and conclusions as I implemented writing to learn in math-ematics. Our definition of WAC @ MEC is this: We define writing across the curriculum as a means to connect writing to learning in all content areas. We define writing as the process through which students think on paper, explore ideas, raise questions, attempt solutions, uncover processes, build and defend argu-ments, brainstorm, introspect, and figure out what’s going on. We define all of these as thinking. Writing to learn across the curriculum provides a potent way for students to exercise their own voices as well as to take on new voices which represent their knowledge of the content and the language of the discipline they are learning (Lester, et. al, 2000, p.4). The words that I have underlined gave me the idea of what the concept of writing to learn in mathematics should be–learn-ing the new language of the new discipline.