This multi-disciplinary course on scaling will use the unifying theme of size to examine a wide range of physical and biological systems. In each case we will see that "size matters". This will be shown true in the most basic sense, that of spatial size, shape, area and volume. In a more general sense this truism holds in that the geometry, kinematics, and dynamics of phenomena are largely determined by the relative size of underlying factors and processes. We will identify a set of general scaling laws that reflect these facts, and learn a set of conceptual, graphical, and mathematical tools for working with them. Both the laws and the tools transcend traditional disciplinary boundaries within science and beyond science.