Design based on Conic Sections (Equations of Ellipse).
Students will learn how to modify a non-function equation to an equation of a function which can be used on a graphing calculator. They will visually see when the equations are written separately for the upper half and lower half of the ellipse.  
Students can create a design bases on their own set of equations. They can create any design of which equations can be written. Students love to create their own design rather than duplicating.