Overall, you're doing a pretty good job with your work here, but there are a few things I want to draw your attention to in order to keep you on the right track.

Starting with your organic intersections, these are solid. You're doing a good job of demonstrating your understanding of how these forms relate to one another in 3D space, your cast shadows maintain consistent light sources and wrap believably around one another's surfaces, and I'm quite pleased to see you trying it without contour curves and being able to maintain the same general solidity.

Moving onto your animal constructions, there's definitely a lot of exploration and experimentation here as you work to get your head around the concepts covered here. As a result, there's a lot of good development of your understanding of how to approach constructing these animals, but there are also some places where you deviate a little here and there.

One area where you definitely experimented a lot was with head construction. As with most things, as long as you're thinking about how the things you're building up exist in 3D space, it's not exactly that you're making mistakes, but rather that there are some experiments that went better than others. For example, the head on the otter in the middle of this page came out quite well for a couple reasons. Firstly, you were very generous with the space you gave the eye sockets, and you were also very specific in how you designed those eye sockets. By orienting the point of those shapes downwards, you gave yourself a little wedge in which the muzzle could fit, and a flat surface across the top where the brow ridge could be set. This produced a nice puzzle with all the pieces fitting together nicely.

We can contrast this with this hippo's head where the eye sockets each touch the muzzle section on one corner each, and that's about it. Around them we're left with a lot of open space, leaving them feeling like they're all but floating freely of one another, and undermining the resulting solidity. Providing it with bigger eye sockets (remember that eye sockets can and will be a fair bit bigger than the eyes themselves, so don't limit yourself to just what you see so directly) would definitely help here, as would simply starting out with a smaller overall cranial ball. There's no need to go all-in on a big cranial ball this early, and you'll usually be able to work your way up to a bigger head size if it's needed. The reverse - starting big and finding a way to cut pieces off the head construction - is considerably more difficult. You ran into that kind of an issue with this rabbit as well, where its head was just so big that it didn't leave you much room to work.

I'm pretty sure you've seen this, but the current approach I'm pushing for head construction (and which will be made into part of the core lesson once my course-material-overhaul reaches lesson 5) is what's explained here in the informal demos page. As you can see there, the specific shape of the eye sockets is critical because of how they help us break the cranial ball down into a series of forms, all of which fit together tightly.

The next point I wanted to look at was how you approach building up your additional masses. I can definitely see that you are, to varying degrees, trying to think about how the additional masses you add to your construction should be shaped in order to interact with one another in a believable fashion. In a lot of ways, you're making a good deal of progress, although there is still room for growth here.

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.

Think only about this, and the volume of the mass itself, as you design its silhouette. Don't think ahead to how you might add contour lines to make it feel thicker - it's very easy to start relying on additional contour lines to fix our little mistakes, but I find it to be far more beneficial to just leave them out when dealing with additional masses altogether. Just like you managed to maintain the illusion of weight and volume on that second page of organic intersections, you can achieve that here just as well with the additional masses, as long as you put everything into their silhouette.

As a side note, keep in mind that every single element we add to our constructions should itself be a solid, complete, enclosed, 3D form. This is a rule I've broken on some of my older demos, and it's one of the many reasons I'm eager to overhaul this lesson's demo materials. You were definitely abiding by this rule much more as you got further into the lesson, but early on there was a lot of jumping between flat shapes and 3D forms. It's totally understandable, and the less-than-perfect demos are certainly to blame. I'm glad to see that you ultimately did end up working strictly 3D, but all the same I wanted to make this point as clearly as possible.

The last thing I wanted to call out is just how important it is to take your time. It's very clear that for most of these drawings, you are doing just that - you're thinking through each mark, and solving one problem at a time, patiently and carefully. There are however some situations where some of your drawings ended up being more rushed, more sloppy. For example, your porcupines weren't drawn with nearly as much care as most of your other drawings, and there are a few reasons for this:

• It was a difficult problem, so you were getting overwhelmed. As we get overwhelmed, we tend to throw away the basic principles we know, and instead react more on instinct. Instead of panicking, just take a step back and think back to the core principles you are confident in, and work from there.

• You were drawing pretty small, cramming a number of different drawings on the page. Drawing smaller tends to limit our brain's ability to think through spatial problems, and also limits how easily we can draw with our whole arm. Both of these tend to make us clumsy.

• Make sure you're working with high resolution reference images. It's easy to end up working with low-res stuff that our eyes can understand well enough at a general scope, but can simply not provide us with enough information to distinguish major forms from one another. This leaves us struggling, without being entirely sure why.

So! With that, I'll go ahead and mark this lesson as complete. There are certainly things to work on, but I feel your work here makes it clear that you're heading in the right direction, and that you largely understand how you should be thinking about these problems.