The learning goal of optimization is clear, and it can be used for that purpose. However, there is more since we are interested in the parameters for which the situation is such and such... This is much more demanding than simply understanding an optimum, but the flexibility of the material is not so great that it could be used in a variety of different ways. In this simulation, student has to fiddle with the parameters in order to achieve some particular states, such as the maximum perimeter for x=1, which is a=1, and where the maximum is reached for both the perimeter and the area (ba=3 and the rectangle is a square). But the answers to these questions, or the algebraic tools to tackle them, are not given. A parabola in the form of y=-ax^2+b is shown, driven by the parameters a and b, together with an inscribed rectangle between the x-axis and the parabola. The side of the rectangle is draggable. The associated perimeter and area can be drawn. The issue is to understand how these two (quadratic) functions behave and where they reach their maxima, and how this maximum depends on the parameters. The final answer (1/a for the perimeter and √(b/3a) for the area) is not given and not so easy to get so this material is surely intended as an introductory material, or else the prerequisite knowledge is much higher: basic algebra and parabola summit computation.