Jumping right into your organic intersections, these are looking pretty good. You're doing a great job of establishing how the forms slump and sag over one another under the force of gravity, and your cast shadows are doing a good job of wrapping around the surfaces upon which they're cast. Just make sure that you ensure that each form casts a shadow - I noticed that the bottom most on the second page didn't cast any shadows onto the ground plane, and there are a few others scattered throughout that aren't casting shadows when they certainly should.

Before I get into your animal constructions, I think it'd be best to answer your questions first.

How would Uncomfy approach drawing something like bone

So the thing here is that unless an animal actually has a literal exposed bone, we wouldn't be drawing them - or at least, not in the sense that you start with bone, then build up musculature, then wrap it all up in skin. While that is an entirely valid way of approaching the study of animals, that isn't what we're doing here in this course, or in this lesson.

What we're doing here is no different at its core from Lessons 3 and 4 - we are not learning to draw plants, or insects, or animals, but rather we are using each topic as a subject matter, or a lens through which to look at the same problem. That is, understanding how complex objects can be broken up into separate forms, and built back up one step at a time. At the heart of it, each of these drawings are simply exercises in spatial reasoning - each one starts us off at a relatively simple arrangement of basic masses, and looking at our reference we identify which forms we need to add next, and how they ought to be designed or drawn to convey their relationships with the existing structure. It is this process of thinking through how the forms fit together in space that forces our brain to gradually develop its internal model of 3D space.

So in the context of a wing, we are not concerned with bones because we don't actually see them. We're concerned with the forms we can perceive - so the way you approached the wings on your birds (especially the black kite) is more in line with what we want. That said, I would try and focus on ensuring that the base wing structure is treated as though it has volume and thickness to it (as wings do), and that the wings are actually attached to that structure rather than existing within its framework as demonstrated here.

How do you tackle "tapering" form? E.g., the front part of the wings of a bird is thick, but gets progressively thinner as it gets closer to the tips of the feathers. Would you draw the front, thick part as a separate form like the peregrine falcon (in link) or draw it all as one form?

It really depends. There are many cases where drawing it in one form like the black kite is fine - while it's not the simplest structure in the world, it is generally simple enough that with one or two well placed contour lines you can establish the varying thickness from one end to the other. I would however note that on the peregrine falcon, you appear to have added a lot of partial contour lines there - not sure if these were supposed to be more for detail/texture but they don't look specific enough for that. Rather, it looks more like a middle-ground between texture and contour lines, and in being so it doesn't really do a great job of being either.

For contour lines, it's important to draw each one in its entirety and to only use as many as are strictly needed, whereas with texture we have to think about the specific textural form and how it sits in space, so we can imply its presence through a cast shadow shape whose design specifically defines the relationship between the textural form casting it, and the surface upon which it is cast.

Now you certainly can build up the wings through separate forms, but remember that they are forms and not just flat shapes - and therefore any instance where you combine elements together, you need to be defining either how they intersect with one another, or how they wrap around one another.

With that out of the way, I think overall you're doing pretty well with your animal constructions throughout this lesson, but I do have a number of suggestions to offer that should help you continue to get the most out of these exercises, and I'll try and go through each one as quickly as I can, starting with a quick list of smaller points:

• Where in your Lesson 4 work I lauded you for generally sticking to working in 3D space and avoiding jumping back into working in 2D space (which students often do with shortcuts like modifying the silhouette of an existing form rather than adding a new, complete, self-enclosed form to the existing structure), you do take far more liberties here. As shown on this bear I've marked out cases where you've attached flat shapes to the existing construction in order to quickly add elements (and sometimes this would also occur when the fur or line weight you were adding along the silhouettes of a given form jumped to another, resulting in a "bridge" between those forms that encloses other flat shapes). This can also occur in reverse, where students cut into the silhouettes of their existing forms as shown here. These kinds of actions remind us that we're really just drawing lines on a flat page - and in reminding ourselves of that, we also make it more likely that we're going to add yet more marks that further undermine the illusion we're trying to create. Whereas, ensuring that every addition is its own complete form will help to further reinforce the illusion instead.

• Another very good example of the above point is your puffer fish - drawing each of the spines as its own separate structure and defining the actual intersection line to mark out how they relate to the main mass in 3D space. Here's a rough idea of what I mean. Each of the spines here are defined as a complete, self-enclosed structure, and therefore can exist in 3D space (whereas the open-ended ones you were drawing are not so clear). From there, defining the intersection lines themselves also create a more specific relationship between the forms, grounding each of the spines against the larger structure.

• You appear to be rather inconsistent in how much of the sausage method you're applying here - there are a lot of cases where you're not sticking to simple sausage forms, others where you use ellipses rather than sausages, and yet more where you do not define the joint between the segments with contour lines. Note and follow every point from this diagram. I should also mention that when drawing your animals' feet, using boxier forms with strategic placement of corners (which help to imply the distinction between the different planes of the form) can help a great deal, as shown here on another student's work.

• While you're making good headway on the use of additional masses, and I can see you thinking through some of the aspects of how the design of each one's silhouette wraps around the existing structure, this can be improved further. 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.

• Separating this into a different point for readability, here's how this can be approached on your elk - note specifically how we're focusing heavily on specifically where we place our inward curves (they only occur when pressed upon by other specifically defined forms). Furthermore, we're taking advantage of the shoulder and hip masses to give us more structure to press up against, to create a generally more grounded and solid result. Also, note that when a mass is added to the construction, it becomes part of the existing structure, and thus anything you add later will then have to wrap around it.

The last thing I wanted to call out was abnout head construction. Lesson 5 has a lot of different strategies for constructing heads, between the various demos. Given how the course has developed, and how I'm finding new, more effective ways for students to tackle certain problems. So not all the approaches shown are equal, but they do have their uses. As it stands, as explained at the top of the tiger demo page (here), the current approach that is the most generally useful, as well as the most meaningful in terms of these drawings all being exercises in spatial reasoning, is what you'll find here on the informal demos page.

There are a few key points to this approach:

• The specific shape of the eyesockets - the specific pentagonal shape allows for a nice wedge in which the muzzle can fit in between the sockets, as well as a flat edge across which we can lay the forehead area.

• This approach focuses heavily on everything fitting together - no arbitrary gaps or floating elements. This allows us to ensure all of the different pieces feel grounded against one another, like a three dimensional puzzle.

• We have to be mindful of how the marks we make are cuts along the curving surface of the cranial ball - working in individual strokes like this (rather than, say, drawing the eyesocket with an ellipse) helps a lot in reinforcing this idea of engaging with a 3D structure.

As a whole I'm not too concerned about how you're constructing your heads - in general your constructions are pretty solid and demonstrate a strong grasp of 3D space, but I would still encourage you to try your best to employ this method when doing constructional drawing exercises using animals in the future, as closely as you can. Sometimes it seems like it's not a good fit for certain heads, but with a bit of finagling it can still apply pretty well. To demonstrate this for another student, I found the most banana-headed rhinoceros I could, and threw together this demo.

The main reason for this - and really for all the principles I've outlined above - is that it helps reinforce the exercise that we're doing. Again, it's not about drawing animals, and so these approaches do not necessarily fit everything perfectly (that head construction approach can deal with some situations with open mouths for example, but it does have its limits), but it is the use of this technique that gets the brain's gears turning towards our goals for this course.

Now, I was somewhat on the fence about assigning revisions - I would normally do so to make sure you understand the concept of avoiding cutting into your silhouettes or jumping back and forth between 3D and 2D, but based on the general quality of your work, I do not think it will be necessary. Just be sure to review the examples I've provided here - and also, it wouldn't hurt to take a look at the specific manner in which the shrimp and lobster demos from Lesson 4's informal demos page have been done. They focus very heavily on ensuring that every step reinforces how the structure is solid and 3D, and avoids adding anything as a partial shape.

So! I'll go ahead and mark this lesson as complete.