shading
How to Draw and Shade a Sphere or Ball – Step by Step Drawing Tutorial

Today I will show you how to turn a circle into a 3-dimensional sphere, ball, or orb. In order to turn a circle into a sphere, you will need to use specific shading techniques to accomplish this. In this tutorial, I use graphite pencils, H, 2B, 3B, and 4B. This lesson will help you learn how to shade a beautiful sphere.
How to Draw Pyramids : Guide to Drawing Pyramids from Different Angles for Beginners

Here is a huge guide to drawing pyramids from all different angles and viewing points. I also show you how to draw a perfect pyramid, using a cube. There is also a pyramid drawn from above (aerial view) that will help you as well. I will show you what these pyramids look like with different shadows, as well as how to draw a pentagonal pyramid, with many sides.
How to Shade Cubes : Adding Shadows to Cubes

We will show you each step to be taken in shading a cube in this tutorial, for this solid is a representative of all prisms, and, indirectly, of the cylinder. Place the cube on a sheet of light brown paper, and pin against the wall behind it a similar sheet to serve for background. Let the light fall from the right and from above the cube. The top face will be the brightest of those seen, and the darkest will necessarily be that next the cast-shadow.
How To Add Shadows to a 3D Cube (Shading Cubes) Step by Step Drawing Tutorial
STEP 1
Draw the cube carefully (reference this cube drawing tutorial here)and lightly in charcoal. Incorrect lines may be removed by dusting with the tinder. Do not draw with black-lead, as it is greasy, and will afterwards appear white in your shading.
How to Shade and Add Light to Complex Forms, Shapes and Objects : Drawing Tutorial
Learn how to see the whites, grays, and blacks in your drawings so you can form 3-dimensional objects. Drawing the light and shadows in forms and objects is a hard thing to learn, but hopefully this tutorial will give you some methods and techniques to use in your future drawings.
How to Shade and Add Shadows to Cartoon Characters and Objects Tutorial

We have already posted an article about shading cartoons and comics...so you can consider this part 2 of the cartoon shading tutorials. This article will discuss sketching simple objects and people in different positions in relation to a light source and how it affects the shadows and shading of that subject.
How to Use Shadows and Shading in Comics / Cartoons Drawing Lesson

Shadows are dark tones which result from some object being in the direct path of light, while shading in a drawing represents the tones on an object that vary from dark to light according to the way the light strikes it. Though comic pictures seldom need any elaborate use of shadows, the forms of figures and objects are brought out effectively by shadows if drawn correctly.