Starting with your organic intersections, for the most part these are quite well done, except for the few places where you've got some sausages that appear to just float, partially supported on one side, but otherwise unaffected by the forces of gravity. Be sure to avoid these kinds of things - whenever you add any form, always add it on top of the pile - meaning whatever already exists is what's going to be able to hold it up, and if there's nothing to support it on one side, it'll have to sag.

Moving onto your animal constructions, there is definitely a lot of good here, but that doesn't mean there aren't issues I can point out to help you continue growing. The first image I zeroed in on was one of your bears, and I marked it up a little bit. Overall it was actually pretty good, but there are some concerns:

• When adding additional forms, you're doing an okay job of wrapping them around the existing structure, but you are somewhat prone to forgetting about some of the bigger masses that would be present - for example, shoulder and hip muscles, which are always "big" engines, even if they're a bit obfuscated by a heavy layer of fur.

• Be sure to be mindful of the ground level - you may even want to pin it down before drawing the animal's legs, so you can consider roughly where each foot should be touching it, to avoid inconsistencies.

• When it comes to paws, I usually opt to draw a simple form whose planes are defined by the actual silhouette - a corner can easily imply the border between front and side planes without needing to add extra internal lines.

• The eyesockets are particularly important in head construction because they are the first step we take to break those curved surfaces into more structured planes. Always remember that head construction is the process of making more specific planes, and establishing borders, as well as connections between the different facial elements. We can push this farther, even into the forehead region, and defining the cheek structures.

Moving forward, another thing I noticed was that when you build many of your additional masses, you tend to build it more like a rectangular form with clear corners to it. Corners should only ever come about when the form is wrapping around some structure - otherwise it should always opt for a smoother curving transition. Think of these additional masses as a big piece of meat - meat's not going to have its own corners until you press it against something else. You can read more about how we shape these additional masses here.

Similarly to this, we want to by all means avoid the sort of "hotdog in a bun" appearance that we get on the back thigh of this elephant. Try not to end up with gaps like that, and definitely avoid such straight ones if you can. As shown here, it looks more natural if these masses curve around the underlying structure. You can also see this in action here and here. For the smaller masses that tend to form at the joints of legs, this may also help.

This isn't a criticism, but I felt the head on this cat was so well done that it was worth pointing out.

With this nile crocodile, I think it's fair to say that you dropped the ball a little in your observation of your reference here. Or a lot. But pushing that aside, there is one thing I want to call out. Looking here, you'll see that I marked out three areas in your drawing where you manipulate the silhouette of some of your forms. The silhouette is not the same as the form itself, and modifying it by either cutting across it or extending it arbitrarily is not the same as doing so to the three dimensional form. Instead, the silhouette is like the footprint an animal leaves behind in the mud. We can tell a lot from it, from the type of animal to its size and how fast it was moving - but if we change that silhouette after the fact, it does not change the nature of the animal. It simply makes the footprint less useful.

Silhouettes work in the same way. They are two dimensional shapes on the page, and if we simply modify them as they are, we are simply changing the two dimensional information so it no longer accurately reflects the actual 3D form it represents. We end up instead breaking that relationship between them. Instead, in the case of the two points along the base of the neck and the base of the tail, if you want to bridge across some forms, you do so not by enveloping those forms in a 2D shape, but by adding another additional mass there to cover the distance. In the case of the head, you need to build off the head's cranial mass, respecting its solidity, and attaching other forms to it. You know how to do this, and you've done so correctly throughout this lesson's homework - so it's odd that you went off script here.

The last thing I want to mention is a fairly minor point - you tend to use a lot of contour lines. Not as many as some students, but still likely more than you need. Contour lines that sit along the surface of a single form aren't actually needed as often as one might think. When forms' relationships with their underlying structure are well defined by their silhouettes, or through the contour lines that define those intersections, those forms often already end up feeling solid and three dimensional. Beyond that, if we do need an additional contour line to help reinforce the illusion of form, it's rare you're going to need several. Always assess exactly why you're adding a contour line (or any line for that matter), determine what it is meant to contribute and whether it is actually needed, before going through the process of drawing it.

With those points mentioned, I'm going to go ahead and mark this lesson as complete. Be sure to keep these things in mind, and practice them on your own as you continue forwards.