The central role that tasks play in student learning has become clearer in the last decade. As a result of calls for a structured design process, task design has become one of the main fields of investigation in mathematics education. Here, we propose five design considerations (deciding on the mathematical content, choosing the context, deciding on the level of structural openness, choosing representations, and arranging a task sequence within an activity). We show how these considerations influenced the design of an activity and compare students' actual work while solving this particular activity and the designers' considerations.