Starting with your organic intersections, you've done a pretty good job in establishing how these interact with one another in 3D space, and have established a believable relationship between the forms that suggests the presence of gravity bearing down on them, causing them to slump and sag over one another.

Moving onto your animal constructions, there's a bit of a mixed bag here. You're demonstrating a developing understanding of certain concepts, but there are a number of steps/things you're skipping, and I think that with certain drawings you perhaps didn't observe your references as carefully and as consistently as you did with others. To this last point, there are also definitely circumstances where some reference images made it more difficult to discern the structure of animals beneath the fur (especially with bears), making that consistent and successful observation a lot more challenging for you to pull off.

First, it's important that we talk about exactly what constructional drawing is, in what ways we can follow its principles, and in what was we can potentially break away from them without realizing it. Constructional drawing is an exercise that develops our ability to understand the forms we draw as being strictly three dimensional. Not that they're flat shapes on the page, but actually being able to comprehend how they sit in a three dimensional space that we can see through the window of our piece of paper. Obviously none of these things are three dimensional - it's all just lines on a page, and so as discussed back in lesson 2, what we're doing here is telling a lie. But to tell a lie convincingly, we need to be convinced of it ourselves. We need to believe in the lie we're telling.

The fact that we're just drawing on a page gives us a great deal of freedom to put down any kind of mark we wish - but that does not mean that the marks we draw will all serve our purpose. In fact, the majority of marks will undermine the illusion we're trying to create, and break the viewer's suspension of disbelief by reminding themselves that they're just looking at a flat drawing. That's why our own belief is important - if we believe in the illusion we're creating, then it's that much harder for us to put down marks that don't reinforce that illusion. If you believe a surface is three dimensional and rounded, then your brain won't let you draw a straight line across it - that line will have to curve along with it, because that's what our brain believes to be true.

Ultimately what this all means is that when we're constructing our objects, every mark we put on the page must define a three dimensional form that is being added to the construction. We can't draw shapes, we can't seek to modify the silhouette of forms (as the silhouette itself is just a 2D shape), we can't draw individual lines that sit on their own - every single thing we add must be its own three dimensional form, and we must believe it to be as such. To go further than this, we need to understand how the forms we draw actually relate to one another, how they interact with one another, how they intersect and wrap around one another. We cannot simply draw a mark on the page to figure out how it's going to be three dimensional later on.

This brings me to the first major issue I'm seeing - you tend to use a LOT of contour lines. Now, there are a couple different kinds of contour lines, and they are not all of them equal. What you tend to use most of all are the contour lines that sit on the surface of a single form - they're how we initially learn about contour lines back in Lesson 2's early exercises, because they are the easiest to understand. It's the idea that you can put down a flat shape on the page, and then turn it into something 3D after the fact.

These kinds of contour lines tend to suffer from diminishing returns - that means that your first contour line may have a good deal of impact, but the second is only going to reinforce the first. The third, the fourth, etc. will steadily contribute less and less, making them largely pointless additions. So if you look at something like this elephant, which is entirely covered in contour lines, only a small handful of them are actually contributing anything at all to the drawing.

It's important that with every single mark you draw, you think about what job you want that mark to do for you before you draw it. Since we're still applying the ghosting method to every single mark we draw, this occurs in the planning phase. You weigh the task a line is meant to accomplish, consider whether it is the best mark for the job and whether or not another mark is already accomplishing that task. Only draw it if it's actually going to contribute in some way.

Now, the other type of contour line is more of what we saw in the form intersections exercise. These contour lines define the relationship between multiple forms - they establish precisely how they relate to one one another in 3D space. These contour lines are significantly more effective than the first kind, because of how they create a connection between forms where each form reinforces the illusion that the other one is three dimensional. With a single such contour line, you can make an entire structure feel significantly more solid and believable - they're incredibly effective and valuable, and often make the first kind of contour line unnecessary.

This kind of contour line is used as part of the sausage method - it's demonstrated in the middle of that linked diagram. Looking at your homework, however, while you are indeed attempting to use sausage forms to construct your animals' legs, you neglect this critical step of the sausage method. It is extremely important that you reinforce the joint between the sausage forms with a single contour line. This principle isn't just used for the sausage method either - the relationships between all interpenetrating forms should be clearly defined, as this will further strengthen the illusion that what you're dealing with is three dimensional, and will even strengthen your own belief in it.

That is ultimately the primary goal - we're not concerned so much with the viewer as much as we are with building a belief and understanding within you, of these drawings as being real, three dimensional things. After all, if you can come to believe it, you'll have no trouble convincing others. Of course, that's why we draw so many of these things - it takes time to actually develop that belief, it's not something that can simply be explained.

Stepping back to the importance of every single mark we draw introducing a new, solid, three dimensional entity to a construction, I want to look at how you're tackling a lot of the forms you add to your constructions. Looking at this elephant, I've drawn a bunch of places where you've attempted to add additional masses, but did so by only drawing lines rather than complete, entire three dimensional forms of their own. As you can see, none of these colour-coded lines actually enclose a volume or give any impression of being three dimensional on their own. Instead, if you look at the bottom left where I've drawn a sausage and placed a form atop it, that pink form is both complete/enclosed and defines a relationship with the form underneath it by wrapping around it. In this regard we're taking the concept of a contour line and actually using an entire form to wrap around another. This creates a strong connection between them, and makes them both feel three dimensional without ever having to add any internal contour lines.

You can see numerous examples of this in the informal demos section of this lesson, especially the puma demo. Every additional mass - whether it's muscle or even fur (like in your mountain goat) should be added to the construction in this manner, creating a clearly defined relationship with the underlying structure.

Now, this critique has gotten very long, so for now I'm going to leave it at that and give you the opportunity to do some additional drawings while applying this. I'll continue on with your next step and point out other areas to work on, once this more critical concern has been taken off the table. I'll assign the additional pages below.