Starting with your organic intersections, these are looking pretty good. You're doing a great job of establishing how these forms interact with one another in 3D space. One minor thing I did notice though was that the shadows cast by these forms onto the ground plane appear not to follow the behaviour of the other shadows cast upon the ground - instead, they seem to be set at a different angle. When the shadows transfer from being cast upon a sausage form to the ground, there needs to be a sharp change in their shapes.

Continuing onto your animal constructions, as a whole you're off to a pretty good start. I definitely think that your heavy focus on detail/texture ends up being a bit of a distraction, and I'll address that in a bit, but as a whole there are many clear areas where you demonstrate a well developed understanding of form and construction. There are however some areas that we can continue to improve upon.

The first point I want to mention is that the way in which we shape the silhouettes of our additional masses depends on what forms it is pressing up against. By default, our forms start out as simply as possible - like a ball of soft meat, floating in the void, it's going to be pretty circular, made up only of outwards curves. As we press it against our existing structure however, where it makes contact with other forms that refuse to budge, the silhouette of our mass will start to curve inwards, gaining in complexity and forming corners where it transitions from outward to inward. You can see this explained here in this diagram.

The reason this is important to understand is that it means that the shape of our additional masses' silhouettes, once they're actually attached to the body, is not arbitrary nor is it random. It is not subject to how we'd like it to appear - it is subject to the forms it presses against. And therefore whenever there is any kind of complexity forming along the silhouette, there must be a concrete form existing as part of the structure that it presses up against in that area. We need to understand not only this additional mass, but also every single thing it touches, and even define those forms themselves as part of our construction.

So, let's take a look at this border collie, specifically this form along its underbelly. There are a few issues with it. First, let's look at the side of it along the bottom that isn't pressing up against anything. It does have at least two notable changes in trajectory (corners), but with nothing to actually create them. Looking then along the upper side of the mass, where it does actually press up against the dog's torso, we're not getting any of the reactionary inward curving that we ought to be seeing. Instead, the form would look something more like this. Smooth, simple curve along the underside where it presses against nothing, and nice inward curves to wrap that form around the torso structure itself.

As a side note, remember that we're building something three dimensional up here. We can't treat it like a drawing overwhich we have full control to make whatever marks we wish. Instead, we have to restrict ourselves into actually treating it like a physical, three dimensional model that we're piecing together. As such, every element we add to the structure must itself be a solid, three dimensional form, completely defined in its own right, and then defined in relations to the existing structure. Looking at these two individual elements I've colour-coded, these aren't complete forms on their own. They're just lines, relying on the existing structure to fully enclose them. Fortunately this isn't a mistake you make often, and you quite frequently build up your forms as fully enclosed silhouettes.

Before we get more into structural things, let's take a moment to talk about detail and texture. This course obviously isn't focused on that, but we can still at least look at a few areas where I feel you're going a bit off track. Here are some notes directly on one of your drawings.

While you're definitely investing a lot of time into adding fur/detail to your drawings, I think the key issue is that it's too spread out. Instead of putting time into designing individual tufts carefully and purposefully, you're drawing more individual tufts and spikes of fur that tend to repeat the same kind of pattern throughout. This happens easily when we fall into an auto-pilot routine, repeating the same shapes and marks instead of thinking through each one.

The key with texture is often that less is better than more. Our goal is not to decorate our drawing, but rather just to get more information across to the viewer. Strive to do this with as few marks as you can manage, and lean on the fact that the viewer's brain is going to fill in gaps for you.

Additionally, when it comes to other textural marks like wrinkles, remember that it is best to draw all your textural marks as shapes, rather than lines, using this two step process. Intentional shapes can convey far more dynamism, whereas lines tend to be more uniform and static as shown here.

Back to the topic of structure, looking at your elephants I noticed that you got a little lazy when it comes to certain aspects of your additional masses. You tended to rely more often on bridging across forms with flat shapes (rather than forms), and didn't allow your forms to overlap as they should. I pointed out a number of issues here. You can also read more about how to work with overlapping additional masses in these notes.

Alongside those points, you should take a look at how I wrap additional forms and twist them around the sausage struccture in this dog leg example, as well as this ant leg example. This often comes off far better than just lining up additional masses in a straight line along the side of a leg. It's also worth considering the forms that exist along the inside of the leg's silhouette, rather than just those that impact its edge.

Lastly, the elephant's head definitely drifted away from some of the points you were applying much better in earlier drawings. So, I'd like to point you to this general head construction demo. Take a look at the diagram as well as the written explanation, it should help you better grasp how to think about constructing heads.

So! I've laid out a fair bit of information, so I'll leave you to absorb it. Once you've had a chance to go through it a few times and process it, I'd like you to work on 4 additional pages of animal constructions. Better that you stay away from texture/detail for these, and focus on pushing construction as far as it can reasonably go.