Proportions are a pretty common area of difficulty for students, and that does make sense, as it's not something we really address that closely in this course, because it's not up there in one of our major focuses. I've got plenty of students whose work I consider successful where the proportions are off, but the way in which all the pieces fit together is still believable and realistic. In those situations, it's almost as though whatever it is that the student was studying was itself malformed, and they simply captured it faithfully. As far as the main focus of this course - being in developing strong spatial reasoning skills, and in the exercises themselves being a series if 3D spatial puzzles - it still works out fine.

That said, one major contributing factor to one's ability to capture accurate proportions comes down to how carefully (and how frequently) they observe their reference. It helps to inform the nature of the forms they choose to draw. Now it's inevitable that there will still be mistakes between what they intend and what they actually end up putting down on the page, but ensuring that we're investing as much time as we can into studying and observing the specifics of our references and the forms we carry over into our construction is key. This also helps us note more of the subtler nuances in the structure, which serve to make our constructions feel more believable even if those proportions are off. When we don't observe our reference frequently and consistently enough, we become more prone to oversimplifying based on our memory, which can remove those subtler elements and make our constructions feel more cartoony.

Now! All that said, let's actually take a look at your work. Starting with your organic intersections, you're doing a good job of establishing how these slump and sag over one another in 3D space under the force of gravity. That said, you are currently using inconsistent light sources for your shadows, allowing some to cast towards the left and others towards the right. These have to be consistent, coming from a single light source that you've chosen, and as you design each shadow shape, you need to be consciously thinking of where that light is coming from.

Continuing onto your animal constructions, there is definitely a lot of good here in terms of how you're gradually building up complexity in successive phases, and working with additional masses to work one step at a time. That said, there are definitely improvements that can be made, and benefits we can achieve by investing more time into thinking about how certain elements are designed.

The most notable issue I caught was that when you work with additional masses, you are working somewhat intentionally at times in how you shape those structures, but it's pretty inconsistent. In this wolf for instance, you have a greater tendency to draw the masses as somewhat arbitrary blobs, not quite thinking enough about how to design each mass's silhouette such that it wraps around the existing structure. Here's how some of them could have been improved.

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.

There are definitely places where you appear to be trying to apply this, it just needs to be given more time. You can also make a point of defining the larger shoulder and hip masses (which are generally where the muscles are that help the animal walk and run), so that you have something around which to wrap the other masses, creating a interlocking puzzle of sorts.

Speaking of puzzles, I can see that you have definitely made an effort in constructing your animals' heads such that all the pieces wedge together, which has definitely helped you to develop more solid, grounded results that feel more three dimensional. It does appear you're applying the principles from the informal head construction demo, though note that you're leaving out a defined forehead. Also, look at the particular shape of the eye socket a little more closely - it's more of an upturned pentagon, leaving a wedge shape in between for the muzzle to fit into, but a nice flat surface across the top for the brow ridge/forehead to rest upon.

In general, I think you will continue to see more improvement if you try to make those eye sockets a little larger as well, also giving you more room to make the eyeballs larger too. This will, in turn, help give you more room to think through how the eyelids actually wrap around the ball structure. You're definitely moving in the right direction in that regard, but there is definitely a lot more that can be done in exaggerating just how those masses wrap around the spherical eyeball, as shown here.

Now, I definitely do feel that the points I was raising earlier in more general terms - about the importance of investing lots of time into observation, and to do so constantly throughout the process to help inform the nature of every mark and form we add to our construction - does apply to you here as well. Again, you are moving in the right direction, but keep pushing yourself to put more time into each construction, to find more things to observe and study, and to simply take more time in deciding how you're going to design each and every mark you put down.

This applies to things like fur texture as well - you appear to be putting it down a little more haphazardly at times, as individual one-off spikes. Taking more time to design each and every tuft, and to really control how they come off the silhouette of the form and return to it (you often have marks that seem to cut across that silhouette line, not quite stopping at it, but a little beyond it).

Ultimately there are two things that our drawings benefit from being given throughout this course - space, and time. In giving our drawings more space, we're able to give our brain more room to think through spatial problems, while also making it easier to engage our whole arm while drawing. This is something you're doing decently at (although when things get particularly cramped, like in the head constructions and around the eyes especially, it does get a little clumsier). When it comes to time however, it is normal for students to feel that how much time they can offer a drawing is somehow externally limited - that they have to complete a drawing within a single sitting, that as soon as they get up, the drawing has to be called done. When you think about it though, there's no actual reason for that - our drawings can be spread out across as many sittings as we want, and as many days as we need. All that matters is that we invest as much time as the drawing itself requires of us, not that we try and shoehorn the drawn into what we have to offer it.

In order to push this mindset shift, try to avoid completing more than one drawing in a given sitting, or in a given day. Of course you're encouraged to give the drawings more than a day, but this works as a baseline to ensure that you don't limit yourself further by trying to get way too much (like, multiple drawings) done all at once, which is a common source of rushing. It's not at all uncommon for students to feel that they simply dont know what else to do to fill up the given time, but when imposing this one-drawing-maximum-per-day limit, it can help one to better explore just where their time can be invested.

So! I'm going to assign a few pages of revisions below, and I'd like you to do no more than one in a day - bonus points of you split them each across multiple sessions and days.