This tutorial is a Photoshop-based "side project" that I like to offer to students as a suppliment to different projects (i.e., web design templates) that we will be working on. The instructional goal of this tutorial is to provide students with a value (as in light and dark) based system of shading that utililizes a numeric scale of percentages. The student objective is to be able to compose a three-dimensional shape using a fairly basic system that incorporates both geometry and basic math.
I have attached the PDF files (above) for further viewing.
