In early 2008 researchers from the University of Melbourne's "New Technologies for Teaching Mathematics" project created a lesson for the Year 10 students at their Victorian research schools. Two important goals of secondary school mathematics education are to build students' conceptual knowledge and to teach students to think mathematically. Mathematics education research supports the notion that seeing concepts represented in multiple ways both supports students' sense-making and enriches their learning. However the experience of working with multiple representations is not the same for experts and novices. The design of lessons must be carefully considered in order not to create excessive cognitive load for the learner. The study by the University of Melbourne team focused on one "lesson", designed to provide exemplars for lessons where new powerful, mathematically able integrated documents (Nspire) are used to support students' exploration of various representations of a given mathematical problem. Based on applications of quadratic functions, "Marina's Fish Shop" was designed as a capstone lesson utilising TI-Nspire CAS computer and handheld technology in exploring multiple representations of a mathematical problem set in a real world context. In this article, the authors provide a description of the problem setting and the six carefully guided student activities that formed the final product of that process: (1) observing variation; (2) calculating total area; (3) graphing the area function from data; (4) finding the minimum area from the graph; (5) finding the minimum area exactly; and (6) challenge: producing a general solution. (Contains 7 figures.)