As a whole, I think you've done a fantastic job. There are a few things I want to draw your attention to, but overall you're doing a great job with all the core principles of the lesson, demonstrating extremely strong spatial reasoning skills, and a well developed grasp of how to build up these complex structures without losing the illusion of solidity. You've done really well, and should be proud of yourself.

So the main thing we explore throughout this lesson comes down to the use of additional masses. In a lot of places, you're using them really well, but there are ways in which certain areas can still be improved.

Let's take a look at this dig, which I marked up quite vigorously. When it comes to the additional masses, there are a few points I want you to focus on:

• In situations where you've got two masses overlapping one another, remember that these are 3D forms - that means that when you drop a new form on top of another one, it's not just going to occupy the same space. You need to think about how the new one wraps around the existing one, to define the relationship between them more effectively.

• Always make sure you're drawing each form in its entirety. There may be places those forms get hidden behind other structures - like the legs - but draw them anyway, so you can understand fully how they sit in space.

Sometimes it can definitely be difficult to figure out how exactly the silhouette of a form needs to be shaped. One thing that helps with the shape here is to think about how the mass would behave when existing first in the void of empty space, on its own. It all comes down to the silhouette of the mass - here, with nothing else to touch it, our mass would exist like a soft ball of meat or clay, made up only of outward curves. A simple circle for a silhouette.

Then, as it presses against an existing structure, the silhouette starts to get more complex. It forms inward curves wherever it makes contact, responding directly to the forms that are present. The silhouette is never random, of course - always changing in response to clear, defined structure. You can see this demonstrated in this diagram.

As I marked on this deer in blue with the big forms you tend to do pretty well with them, swooping them down and wrapping them nicely - although as I showed in red along the rump area, it's really important and useful to consider other forms like the big hip mass, and how your forms will wrap around it.

Getting back to the dog, I also pointed out a few other points:

• For head construction, take a look at this explanation if you haven't already. It points out the use of a particular pentagon shape (with the point facing downwards) which works really well for eye sockets. It provides a nice wedge to fit the muzzle in, and a flat top across which we can lay the brow ridge. Also, make sure that when you're drawing that muzzle, you're pinning down how it connects to the curving surface of the cranial ball - you appear to have cut straight down instead.

• Leaving the feet in a relatively simple state is a common mistake - there's no reason we can't push a little further and construct the toes as a few boxes.

• For the contour curves defining the joints in your sausage forms, remember that the degree can't just be random - it specifically communicates the orientation of that cross-sectional slice, relative to the angle of view. I recently updated the ellipses video, and I feel my explanation of the degree and how it relates to the circle's orientation in space has been improved a fair bit. Give it a watch if this isn't entirely clear to you.

• When drawing fur, it's easy to fall into auto-pilot mode and draw repeating shapes. When drawing those tufts, you want to be more purposeful and intentional in how you design each one, to ensure that they don't just look like a repeated pattern.

To finish things off, your yoshi was pretty cute! Although it's worth mentioning that your linework here actually got kind of scratchy/sketchy. Definitely keep an eye on that. Remember that every mark should employ the ghosting method to maintain smooth, confident strokes.

Anyway, keep up the great work. I'll go ahead and mark this lesson as complete.