Overall, you've done a pretty fantastic job. Starting with your arrows, these are spot on. You're doing a great job of capturing how each of these flow fluidly through 3D space, with a strong, consistent application of perspective on both the positive space (the width of the ribbons) and the negative space (the distances between their zigzagging sections) to really sell the idea that they exist in 3D space.

Moving onto your organic forms with contour lines, you're doing a pretty good job of sticking to simple sausage forms (as mentioned in the instructions). You're also doing an excellent job of keeping your contour ellipses and curves confident, evenly shaped, and snug between the edges of the sausage form's silhouette. You also appear to be applying a strong understanding of how the degree of those contour lines changes as we slide along the length of the form. Very well done!

Now, your textures are really the only place where I'd say you do a good job, but you aren't entirely grasping the concepts covered in the lesson. That's entirely fine - I don't expect students to grasp it just yet, as these two exercises serve as an introduction. You're also demonstrating exceptional observational skills and attention to detail. The issue is however that you're still largely thinking in terms of lines. Your lines may vary in weight, but in most of these you're still perceiving lines in your reference images, and then drawing those lines to match. What's missing is the step in the process where you understand the marks you see in your reference as being shadows cast by actual little textural forms that are present on the surface of the object.

It's these forms that are important - not the lines you see, but what those lines suggest to be present. Then when you go to draw your textures, you don't carry over the lines - you carry over an understanding of the forms that are present, and then think about the kinds of shadows they cast on their surroundings.

The best example I have to show this is in your crack texture in the middle row of your texture analyses. Your focus here has been entirely on the cracks themselves, and the patterns they create between them - not on the chunks of matter between the cracks, the actual solid forms that exist. You identified the spaces between them instead. Ultimately a crack doesn't exist - it's an empty space, an absence of matter. It's in the cracks where our forms cast their shadows, and often that makes these cracks dark, but it does not mean that our shadows behave like liquid, filling in that negative space. The shadows are still directly related to the forms that cast them, and they can tell us a lot about the relationship between the form and the surface upon which the shadow is cast.

It's that information that we want to sneak into our drawing - we're not drawing the forms themselves, but rather implying things about them through the shadows they cast. This isn't inherently easy to understand, and even when understood it can be difficult to get used to applying it.

Now, there are varying degrees of success in your dissections - the kiwi feathers, the beetle shell and the ceiling are among my favourites, with the ceiling being the most successful representation of the concept. Ultimately, when done correctly, you're able to more seamlessly transition from an area of white to a dense texture with no clear jump in between these levels of density. That's what you've achieved in the textures I pointed out above (and a few others as well). You've got others that demonstrate excellent attention to detail and observation of your reference, but they struggle to shift to any other level of density but the one that covers the surface evenly.

Moving onto your form intersections, these are very well done. Your forms are really solidly drawn, capturing a strong sense that they exist together within the same space (rather than just as shapes pasted on top of one another). You've also got an excellent start on understanding how the forms relate to one another through the intersection lines. This is another one of those "introductions" to a concept, but you're definitely knocking this one out of the park. This course as a whole focuses heavily on these principles, and it's something we'll continue to explore throughout subsequent lessons. As it stands though, you're sitting at an advantage.

Lastly, your organic intersections are similarly well done. You're capturing a strong sense of how these forms interact with one another in 3D space, and you're doing a good job of demonstrating the impact of gravity on how they slump and sag against one another.

All in all, very well done. I'll go ahead and mark this lesson as complete, so keep up the great work.