Looking through your work, there's a lot of good stuff here, but there are also a number of points I want to draw your attention to that should help you improve your overall progress here.

The first point I want to make is a big one, and it's one I called out in my critique of your Lesson 4 work: Do not alter the silhouette of a form once it's been drawn. Every addition to a construction must be a solid, complete, enclosed 3D form of its own. Don't attempt to simply "envelope" forms with new silhouettes, don't add lines that only create part of a form (closing itself off by being pressed against the silhouette of another form), and so on.

On this bear I've pointed out a number of places where you broke this rule. In some cases you bridge across from one form to another by simply adding a basic line, but in others you end up "enveloping" the animal in a new layer of fur. That's an understandable mistake - remember that fur is just something we apply to the silhouettes of our forms. There should not be a gap between your fur and the forms it's being applied to. Furthermore, as explained here you should be drawing each tuft of fur with a separate, purposeful mark, designing them intentionally instead of falling into automatic, repeating patterns or mindless back-and-forth. This will ensure you don't break the third principle of markmaking from Lesson 1.

On that bear I also pointed out the fact that you're not adhering entirely to the sausage method when constructing your legs. You're straying by using forms other than simple sausages, and by not reinforcing the joints between forms with contour lines. This last point applies across the board - it helps a great deal to improve the 3D illusion by defining the relationships between forms with contour lines. You did a better job of this back in Lesson 4, so I didn't dwell too much on it, but I did state that this technique would be used throughout Lesson 5 as well when showing you the dog leg demo.

So - there are some pretty big areas where you neglected to apply points that were raised in my last critique. Paying close attention to the feedback you're given and ensuring that you read it repeatedly - even right before doing your Lesson 5 work - is a good idea to keep it fresh in your memory.

The next point I wanted to touch on has to do with how you go about creating the impression that your new, additional masses actually "wrap" around the existing structure. Right now the way you've drawn them does feel more like they're flat shapes being pasted onto the page - but there's a way we can fix that.

The key is to think about first how the additional mass exists on its own, floating in the void. Here it would be in its simplest possible form, like a ball of soft meat or clay, made up entirely of outward curves - since there's nothing there to press in on it. We only start to develop complexity in that silhouette when we press it against the existing structure of our animal. As it makes contact, it develops more inward curves and corners, conforming to the surfaces it's pressing against - though the edges not making contact remain simple. You can see this concept demonstrated in this diagram.

The point is that the silhouette matters. We're not just slapping an arbitrary shape on the page - instead we're thinking about how, when it presses against the other forms, its silhouette is going to purposefully respond to the specific forms it touches. At no point should the form's silhouette have complexity without a corresponding form to cause it, but it also should have some complexity to correspond with every form we know to be present.

Here's some additional masses added to one of your pages of rabbits. I also noted some areas where you opted to take shortcuts, switching from construction to just drawing things from observation without establishing how those structures actually exist in 3D space. Every drawing we do in this course is an exercise in spatial reasoning - so just drawing things purely from observation without first considering how they exist in 3D space (explicitly on the page by constructing them) isn't useful to us here.

Also, I did notice that you have a tendency to go back over marks, or draw a little more roughly. Don't forget that you should be using the ghosting method for every mark you draw, and you should not be going back over marks without a good reason. Line weight, for example, is one potential reason but it has its own rules. It should only be applied in key localized areas to clarify how specific forms overlap one another. It shouldn't be applied to the entire silhouette of a given object or form, just for the hell of it.

The last thing I wanted to offer is that while your head construction is certainly moving in the right direction - you're thinking about the eye socket and moving in the direction of getting the muzzle to fit up against it (though this isn't always fully constructed and defined), I do want you to read through this explanation from the informal demos page. It goes into greater depth about how to think about the different structures of the head and how they all fit together, as well as how the eye socket is the first step to separating a rounded surface into a series of more complex planes.

So, I've outlined a number of things for you to work on. I'm going to assign some additional pages below, so you can demonstrate your understanding of this material.