Starting with your organic intersections, these are looking great. You're doing a good job of piling them up in a way that feels stable and believable, and the forms themselves feel solid and three dimensional.

Moving onto your animal constructions, there's a lot of good here, but there are also a number of issues I want to draw your attention to. I picked on your hyena construction specifically, as it was fairly well done, but could be used to demonstrate the points I want to emphasize to you. I've added notes directly on the drawing here, but I'll address the major ones below:

• Firstly, for your additional masses, you tend to bury them in contour lines, and those contour lines generally don't really contribute much of anything to those forms. If you look at how I drew my own additional masses in their place in red, you'll notice that I didn't actually add any contour lines on top of them, because they weren't actually needed. This is because when drawing them I focused entirely on establishing a relationship between each form and the structure that lay beneath it. In creating this relationship, I was able to believably make that form feel as though it exists in 3D space. By focusing on how that form is wrapping around the existing structure, we bind it more tightly to the construction, rather than giving the impression that it's just a flat shape, or perhaps a 3D form that is resting gently on top (that could ostensibly fall off at any point).

• The thing about contour lines is that they come in different varieties. At its core, a contour line is just the idea of describing how one surface deforms through space by placing another element - be it a line, or in this case a whole other form - such that it runs along that surface. A contour line that sits only on a single surface only goes as far as to make that one form feel solid on its own, in isolation. This can be useful in some cases, but it also suffers from diminishing returns. The first may contribute a fair bit in this regard, but the second less so, and the third and fourth may have no impact at all. Rather than burying your forms with many contour lines, focus on making sure that the contour line you choose to add is executed as well as possible - and before you even do that, look for opportunities in how the form itself is drawn to establish its relationship with the forms around it.

• As there are different kinds of contour lines, there's one that you were missing entirely in your use of the sausage method. As explained in the middle of this diagram, you are to place a single contour line at the joint between each pair of sausages, to help reinforce their relationship with one another. This kind of contour line - the one that creates the relationship between forms - is far more effective than the kind that sits on a single form, as it creates a connection that states if one of these forms is 3D, then so too must the other one be 3D.

• Lastly - and I actually mentioned this at the end of my lesson 4 critique - as there will be many situations where you will want to be able to take that simple sausage structure further to add bulk wherever it's required, you must do this through the addition of more forms, NOT by simply modifying the silhouette of the forms you've already drawn. An object's silhouette is like the footprint of an animal. In finding a footprint, you may be able to identify all kinds of things about that animal without ever having seen the animal itself - how big it is, what kind of animal it might be, etc. But the footprint itself is not the animal, and if you change that footprint, you're not changing the animal that left it. You're just making the footprint a lot less useful. In this sense, modifying the silhouette of a form you've already drawn only breaks the illusion that we're looking at something real and 3D, and turns it into nothing more than a flat drawing. If you want to add bulk to the legs, you need to do so by wrapping further forms around it, as shown in the little example I drew on your page, as well as here.

Moving onto the alligator on which you requested some feedback, an important thing to point out is that the point of this lesson isn't to teach you how to draw all animals - at least, not exactly. This lesson is no different from the last two - it's about developing your spatial reasoning skills by looking at how to combine forms in particular ways, using construction (with specific subject matter in each lesson) as an exercise to develop that skill. You aren't actually tied down to particular approaches or recipes, but for the time being, the cranium-ribcage-pelvis model gives you something to hold onto while you wade out into these concepts. That also doesn't mean it's the best way to approach every animal.

I'm assuming you're working from this reference image, based on the pose. It's definitely a challenging one, specifically because of how far the structure of the gator differs from the other kinds of animals we've tackled. The same principles still apply - that is to say we can still break it down into a series of simple forms - but in this case we might instead want to start out with more box forms, in order to break it down into its major planes.

That said, there are some more immediate issues with your approach. First of all, if I'm correct about the reference image used, the camera angle is pretty sharply different - the reference is angled lower, whereas your drawing is more of a top-down view. There are also numerous issues that I addressed above, in your hyena - additional forms not wrapping around the core of the body as well, and the overuse of contour lines. The legs are handled well, although I'm not sure why you filled the back ones with hatching.

Lastly, because the alligator is so vastly different in structure, especially in its head, from the other animals we've tackled, I think you ended up getting a little bit overwhelmed. In being overwhelmed, you ended up spending more time trying to figure out the construction of it, but not necessarily in observing your reference. As a result, your drawing ended up featuring some definite simplification that is not present in your reference image. Even though construction gives us an amount of freedom to build things out logically, we still need to study our reference closely and constantly to identify which next form we can incorporate. We aren't necessarily bound to the specific recipes covered in the lesson (and to that point, that tiny box you placed on top of the head, around where the eyes were, was an interesting touch), but we still have to make sure the forms we draw accurately reflect what is actually present - not what we remember seeing.

Anyway, I've laid out a number of things for you to work on in terms of your more traditional animal drawings, and so I'm going to assign some additional drawings for you to demonstrate your understanding. I do think that overall you're moving in the right direction, but you do need to ease up on those contour lines and put more focus into how you wrap forms around one another in a believable fashion.