We study the use of a computer application, intended for Computer Assisted Language Learning (CALL). We present an analytical framework for CALL, consisting of technology, interaction with technology, a relationship between technology and students, and a context where technology is situated. The application we study performs several different kinds of state of the art linguistic analyses, and is intended for writing texts while paying attention to linguistic forms. We have conducted a naturalistic field study of two informants use the tool collaboratively. Our question is in what manners these students put the tool into use. These students let initiative be taken by the CALL application, despite it being designed with student initiative in mind, and despite students being aware of features and occasions where they could take initiative. We use our framework to point out how this student-system relationship is formed, and provide guidance for future design.