Tasks are an important part of the education in mathematics. In an ongoing study, an analytic framework for identifying challenges in students mathematical task solving has been developed, and the conceptual and the creative challenge has been defined. Preliminary results indicate that considerations are needed to include these challenges in mathematical tasks. This paper takes off from there to describe a structure for selection and (re)design of tasks. The aim is to be able to discuss the basis for the structure. A further aim is to develop a support for teachers, test designers, textbook authors and others, in creating tasks with specific learning goals.