Starting with your organic forms with contour ellipses, you've nailed the main points I look for here. You're wrapping the contour lines nicely around the form, the sausage forms themselves are (for the most part, with some exceptions to keep an eye on) simple, sticking to the criteria of two equally sized spheres connected by a tube of consistent width, and you're demonstrating appropriate grasp of how the degree of your ellipses shifts over the length of the form.

My only concern here (aside from the few sausages that weren't entirely simple and did show ends that were more stretched, or of different sizes, or where there was slight pinching through the midsection), is just a matter of linework. It looks like you were going back over your contour lines a couple times, resulting in them getting a fair bit darker than the sausage forms themselves. Having darker internal lines messes with the illusion of solidity and cohesiveness, underlining the idea that these are all just lines on the page instead of a 3D form with lines running along its surface.

I can absolutely understand that you likely confused the idea of "drawing through ellipses" as applying to these contour curves as well. To clarify, since the contour curves themselves are partial ellipses with a break in their middle, we do not 'draw through' them as we do with full ellipses, as the gap removes all benefit.

Moving onto your insect constructions, there are a number of issues I want to mention, but I think you do demonstrate a fair bit of progress over the set, most notably at the very end where your dragonfly is definitely the strongest of the bunch. There are still concerns that apply to it, but it does the best job of them all of demonstrating a grasp of how the whole object is made up of many simple, solid forms that relate to one another in 3D space in a clear and concise manner, rather than appearing more as simple flat shapes on the page overlapping one another.

The first issue I want to address is that when it comes to building things up from simple forms, you're not being terribly consistent, often introducing forms that are more complex (like this beetle's thorax form without any real grounding in 3D space. The complexity of the form makes it much more difficult for it to read as being a solid, three dimensional element, and instead can easily remind us that it simply exists as a 2D shape on the page, breaking that illusion we're trying to achieve. We can also see cases like along the end of the back leg, where you've got these little heart-shaped segments layered together, but with no underlying structure grounding them in space.

With the leg specifically, we have a technique we use to achieve this - the sausage method, which allows us to create a solid armature/base structure upon which we can append further masses. The method as demonstrated here involves several important criteria. First of all, the sausage segments themselves MUST be simple, as described at the beginning of this critique, in order to maintain their individual solidity. This is something you're not terribly consistent with. Secondly, the sausages must interpenetrate one another and have their intersection joint defined clearly by a single contour line. Having a contour line that establishes the relationship between multiple forms in space is EXTREMELY effective and achieves far more than contour lines that run along the length of the form can. In most cases, they're all you need, and putting additional contour lines along the length of the segment achieves nothing.

You can then append masses to the segments as needed to add bulk, ideally as demonstrated in this diagram (as it defines again how those additional masses wrap around and relate to the underlying structure).

Stepping back to the idea of constructing everything from simple forms, it's also important that you draw every such form in its entirety. You do this in a number of places - like this guy's legs, where you've drawn the forms completely even where they are overlapped by the thorax. There are other spots however, where you allow the line you draw for a given form to stop where it is overlapped by a neighbour. Drawing the forms completely is an integral part of understanding how they all fit together in 3D space. Again, it comes down to treating them as 3D forms, rather than flat shapes on the page.

Moving onto something a little different, I noticed a lot of areas where you've got some heavy blacks drawn in. While using these to capture areas where one form casts a shadow onto another (which is a great way to separate forms out and make one stand out against an otherwise complex background, it's important that you understand the difference between cast shadows and form shading. These links point to the newly rewritten texture section of lesson 2, complete with fresh new (short) videos which will help distinguish the difference. The important thing here is that rather than cast shadows, you've been shading your forms. I think this might actually be happening because you're attempting to correct mistakes by filling them in with more ink, which is a very bad habit, and one you should break. If you make a mistake, leave it alone and keep going. Adding more ink to a problematic area means that you're going to draw the viewer's attention to those points - and if you allow your mistakes to determine where your focal points end up being, you're going to lose control over the piece.

So, I've covered a number of things here, and it'll take a bit of time to process all of it. I still think you're showing a good deal of improvement overall, and that the dragonfly and how you've combined forms in 3D space for its head and its torso shows that you're picking up the concepts covered in the lesson. Keep that up - we'll be doing a few extra drawings before I let you move forward, so focus on demonstrating those same skills more consistently, while applying the other concepts I've mentioned here.