Starting with your form intersections, these are mostly looking quite well done, with a solid grasp of how the forms all intersect with one another, but there are a few key issues to keep in mind:

• Draw through all freehanded ellipses, as discussed way back in Lesson 1.

• Your linework is mostly pretty good, but there are definitely some places where your linework gets a tiny bit wobbly or hesitant. Always remember that the ghosting method, which is applied to every freehanded mark we draw, ends with a confident execution free from all hesitation.

• One thing that helps a great deal with any exercise that involves a lot of forms packed together in the same scene is to try and keep the foreshortening quite shallow, and whenever possible to avoid making it more dramatic. This helps keep the sense of scale more consistent throughout the scene, as explained here.

Moving onto your object constructions, your work here is honestly extremely well done. You've been incredibly thorough with all of your subdivisions, approaching every aspect of your constructions with considerable precision and accuracy.

To be completely honest, I only have one real issue to point out, and while it's incredibly minor, it is still worth calling out. It has to do with the difference between cast shadows and form shading. Throughout your drawings you've been very bold and confident in using large areas of solid black, and frankly that's great. It shows that you're willing to commit to the choices you make, and these large solid black shapes really help to break your drawings down and clarify what we're looking at through all of the subdivisions and construction lines.

The only thing I want to be really clear on is the difference between what constitutes form shading, and what constitutes a cast shadow. Any situation where you're colouring in a surface because of the relationship between that surface and the light source - like how a surface might get darker as you turn it away from the light, and brighter when you turn it towards the light - is form shading. So for example, looking at this drawing, the far left side of the whole object, which is solid black, that's form shading. Often times whenever you find yourself colouring in the whole face of an object (as you did here, filling in that physical side), it's probably form shading.

Conversely, cast shadows are the result of a form projecting a shadow onto a completely different surface. It is a relationship between the light source, an object, and that different surface. The filled black shape goes on the surface, not on the form casting it. Rather than filling in a given surface, it's usually going to create its own distinct shape on that surface.

The reason this is an important distinction is because a cast shadow will actually, by having its own shape, communicate information about the relationship between the surface and the form. So for example, take a look at this. On the left side, we only get to understand how the box exists on its own, with nothing explaining how it relates to its surroundings. On the right side, we still get to understand how the box exists as a 3D entity (due to how its silhouette is shaped), but we also understand how it relates to the surface beneath it.

This kind of thing comes into play quite a bit when we get into wheels and tires, especially the ones with the really chunky treads where instead of constructing each textural 'chunk', we draw the shadows they cast.

So! With that, I'll go ahead and mark this lesson as complete. Keep up the great work.