Starting with your organic forms with contour lines, one thing from the instructions you may be forgetting at this point is the importance of sticking to the characteristics of simple sausages. You do adhere more to this in the contour ellipses page (aside from the bottom left corner where one end is much smaller and more stretched out, instead of remaining equal and circular in shape), but in your contour curves page you definitely allow yourself to be more arbitrary with your sausage shapes.

Continuing onto your insect constructions, I can certainly see that you're developing more comfort and confidence with this subject matter, and overall there's a lot of good here. There are a number of constructions - for example, your houseflies - where you really lean into the methodology of construction, building things up with successive addition of new, simpler forms as you go, and that's great to see.

There are however some instances where there are issues that I would like to touch upon, in order to help keep you on the right track.

The first of these is the idea of working in 3D space vs. 2D space. Obviously every mark we make is sitting on a flat, two dimensional page, but what matters most is how we treat the marks we make, and how we choose to perceive them. With practice, we gradually train our brains to perceive the things we're drawing as actual 3D forms, but the key to achieving that is to actually treat them as such and avoid interacting with them in any way that would undermine this false assertion.

Given that we're drawing on a page, we have way too much freedom in the kinds of marks we can make as we progress through a drawing. The vast majority of these parks do not reinforce the illusion that we're creating a 3D object - instead, they're more likely to undermine that illusion. In order to maintain that illusion, we must instead adhere to strict rules about what kinds of marks we're allowed to make.

One such rule to keep in mind, is that once you've established a 3D form on the page, you should not attempt to redraw or alter its silhouette. For example, take a look at this wasp you drew. Here you laid down simple ball forms for the original masses, but ultimately ended up cutting back into them, modifying their silhouettes, to achieve a more refined form. The silhouette is just a 2D shape that represents the 3D form in question. When you alter the shape, you don't change the nature of the 3D form - you merely break the connection between them.

Here's what happens when you cut back into the silhouette of a form. It flattens out the construction and results in a mixture of 3D forms and 2D shapes - and the presence of those 2D shapes are what remind the viewer that they're looking at a flat drawing. The same thing ultimately happens when you try to extend the silhouette of a form as well.

The correct approach is to instead build upon your existing structure, introducing new, complete, enclosed 3D forms and establishing how they relate to what's already there, either by having their silhouettes wrap around the new structure (as shown here) or by defining how they intersect with a contour line, like in Lesson 2's form intersections. So for your wasp's abdomen, here are some approaches you could use.

As for other demonstrations of this sort of additive construction, you can see them at play in this beetle horn demo, in this ant head demo, and in this more detailed lobster demo.

Another thing I noticed which relates to this is that you tend to draw your earlier construction lines more faintly, as though you don't treat them as being part of the construction itself. This leaves you in the mindset where you're trying to replace them or get rid of them, and you tend to follow up with more marks that are way heavier in line weight. Make sure that, like you see in the lobster demo (and really any of my demos), you draw the initial masses with the same kind of confidence and commitment as you would any later stroke. Don't build up more line weight as you work through the drawing, stage by stage. Instead, view line weight as something to be applied only at the end of the drawing, to clarify how specific forms overlap one another, limiting it to specific localized areas instead of reinforcing the entirety of a form's silhouette.

Lastly, I noticed that you seem to have employed a lot of different strategies for capturing the legs of your insects. It's not uncommon for students to be aware of the sausage method as introduced here, but to decide that the legs they're looking at don't actually seem to look like a chain of sausages, so they use some other strategy. The key to keep in mind here is that the sausage method is not about capturing the legs precisely as they are - it is about laying in a base structure or armature that captures both the solidity and the gestural flow of a limb in equal measure, where the majority of other techniques lean too far to one side, either looking solid and stiff or gestural but flat. Once in place, we can then build on top of this base structure with more additional forms as shown here, here, this ant leg, and even here in the context of a dog's leg (because this technique is still to be used throughout the next lesson as well). Just make sure you start out with the sausages, precisely as the steps are laid out in that diagram - don't throw the technique out just because it doesn't immediately look like what you're trying to construct.

Overall I think you're making good progress, and I expect the feedback I've given here should help keep you on the right track. You do have somethings to work on, but you should be able to do so as you move into the next lesson. I'll go ahead and mark this lesson as complete.