Overall you're doing a pretty good job here but there are a few issues I want to bring to your attention.

Starting with the organic forms with contour lines, one key thing you didn't quite follow is the importance of adhering to the characteristics of simple sausage forms as mentioned in the instructions. It's not uncommon for students to dive into doing an exercise because they're confident that they remember how it's meant to be done, and as a result they miss seemingly minor points like these. Make sure that you are always aware of all the things that are expected of a particular exercise, by reading the instructions just before you do the work.

Moving onto your insect constructions, overall you have done this well, as I mentioned before, but issue that I'm noticing is that when you put a mark on the page, you don't always treat it as a solid, three dimensional form - or perhaps you will initially, but later if it suits you better, you go on to treat it more like exploratory marks, replacing the forms with something new. We can see examples of this in how you treat many of the later drawings' initial masses. The thorax, abdomen, etc. are drawn more lightly as general ellipses, and then you go back over them - often cutting across their silhouettes - where it suits you. This is not correct.

Every single phase of constructional drawing must be treated as though it introduces a real, solid, three dimensional form into the world. Once it is in place, it cannot be ignored or removed - it's there, and the viewer will understand it as being present, and to suggest that another entirely different for occupies that space will result in the kind of visual contradiction that undermines the solidity of the whole construction. I've highlighted some spots where you've cut across the silhouette of your existing forms here.

There are situations in which we may feel that we're applying "subtractive" construction (cutting back into forms), but the silhouette is not itself a 3D form. It is a 2D shape - like the footprint an animal leaves when it walks through the mud, we can tell a lot about the animal from it. What kind of animal it is, how big it is, how fast it was moving, etc. But if we change the footprint, it doesn't change the nature of the animal - it just makes the footprint less useful to us. The silhouette works the same way. Therefore every change we want to make must come in the form of an action performed in 3D space - adding a three dimensional form that connects to or wraps around that existing structure, or cutting back into the form [as explained here](). Subtractive construction is however something usually reserved for more geometric constructions, so when dealing with organic subject matter, sticking to working additively is always best.

If you find yourself in a situation where the previous construction you'd built up doesn't reflect your reference with full accuracy, don't attempt to take a sharp right turn and make drastic changes. Stick to to the construction as it is. It may not fully match the reference, but that's fine. What's most important is that the construction read as something solid and three dimensional.

Another common cause for accidentally cutting back into a silhouette is when the silhouette itself is an ellipse, and because we draw through our ellipses two full times before lifting our pen, the ellipse may be a bit looser with a gap between the different passes. While this is something we're meant to improve upon with practice, it certainly happens - and it happened a lot in your work. In this situation, always treat the outermost perimeter of the ellipse as being the true outside of the ball form. So you don't want any of it poking outside of your construction.

Moving forward, another thing 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.

Now with those points laid out, I'd like to see a few pages of revisions before I send you on. I'll assign them below.