Choose a side from which light will be hitting the pyramid.
By pressing down lightly with your pencil, draw a light arrow that starts near the light source and shows the angle of the light as it hits the pyramid. If the light source is off of the page (as might be the case if the light source is the sun), start the arrow as close to the source of the light as you can, and indicate the angle of the light as it will hit the pyramid.
Shade the pyramid lightly on the side opposite of where the light will be hitting the pyramid. This will be done by setting the tip of the pencil down on the paper and gently running the pencil back and forth on the surface that should be in shadow. Shade the entire side of the pyramid that does not face the side that is hit by light.
Use a paper stub, cotton swab or fingertip to lightly smear the shadow so that it appears to be evenly shaded.
Shade the ground lightly on the shaded side of the pyramid in the shape of a triangle. The base of the triangle will run along the base of the pyramid, and the point of the triangle will be on the side farthest from the point of the pyramid. This is the shadow of the pyramid, and thus will appear almost to be a mirror image of the pyramid on the ground. The triangle will be distorted depending on the angle of the light. The higher up in the sky that the light hits the pyramid, the shorter the shadow will be on the ground. The lower the angle of the light, the longer the shadow will be.
Use a paper stub, cotton swab or finger tip to lightly smear the shadow so that it appears to be evenly shaded.
Darken the shadows as necessary by running the pencil back and forth gently over the shadows you have already drawn. You may also darken the shadows by pressing the pencil deeper into the paper. This will add depth to your shadows and depth to your drawing. Although you may leave the shadow light if you want, dark and dramatic shadows will make your drawing more interesting to the viewer.
Use a paper stub, cotton swab or fingertip to lightly smear the shadow so that it appears to be evenly shaded.
Clean the shadow with the edges of your eraser by gently smudging the edges of the shadow on the ground so they appear to be slightly fuzzy. This will create a more realistic effect to your shadows.