Starting with your arrows, these are largely drawn pretty well, with both a good sense of flow in how they move through space, as well as a proper application of foreshortening to both positive and negative spaces. I'm pleased with how you're letting the gaps between the zigzagging sections compress as we look farther back.

Now, there is a touch of hesitation in some of your linework. It's very slight, so just try and keep the idea of drawing confidently in mind, and it should resolve itself.

Moving onto your organic forms with contour lines, you're largely doing a good job of sticking to the characteristics of 'simple' sausages as covered in the instructions. There are a few places where a little more complexity gets introduced, but this usually occurs when you hesitate, and the outline of your sausages get a bit wobbly or the shape gets a little deformed. It's clear to me that you're aiming to keep the ends of your sausages circular and equal in size, and also trying to maintain a consistent width through the sausage's length.

Your contour ellipses are largely drawn well - they're pretty evenly shaped, and reasonably accurate in terms of fitting snugly between the edges of the forms. You're also demonstrating a general grasp of how the degree of your contour ellipses ought to shift wider/narrower, as they slide along the length of the form, though do continue to think about how the degree of each contour line corresponds with its orientation in space relative to the viewer.

You've got varying success with the contour curves, though all in all these are mostly well done too. Just don't forget that the contour curves exercise doesn't preclude you from adding the little contour ellipses at the tips of your sausages (when those tips are pointed towards the viewer). The only difference is that with the first half of this exercise, we're drawing with x-ray vision. In the second half, we're drawing only the marks we see. As shown in the example, when the tip faces the viewer we still see a full ellipse.

Your work throughout the texture section is extremely well done. You've done a great job of focusing on the use of solid shadow shapes to imply the presence of textural forms, and to control the density of the gradient as you move from left to right. You're demonstrating really solid observational skills as well, and the shadow shapes you've designed here are very specific and well defined.

This continues throughout your dissections as well - I'm not seeing you falling into the trap of outlining your textural forms at all, and you continue to employ implicit drawing techniques through the entire set. You've experimented with a great many different kinds of textures, and you've done a great job of applying specific, case-by-case approaches to each one, rather than trying to get through quickly with a one-size-fits-all solution.

Looking at your form intersections, to start you're doing a pretty good job of drawing the forms such that they feel reasonably cohesive and consistent within the same space, although you do appear to have missed the instruction on avoiding forms that are stretched in any one dimension, such as your longer cylinders. These should be avoided in favour of forms that are roughly the same size in all three dimensions, so as to avoid having foreshortening making these already difficult exercises more complicated.

When it comes to the intersections, you're off to a good start. We don't generally expect students to have any prior experience with these, so mistakes are pretty common as we just seek to introduce students to thinking about how the forms they draw might relate to one another in 3D space, and how those relationships can be defined within the drawing. That said, your intersections largely do appear to be pretty well done, suggesting a strong grasp of 3D space. One thing though - don't draw them in a different colour in the future. It gives the impression that the intersection lines are somehow separate from the drawing, which can interfere with how we think about them.

Lastly, your organic intersections are generally coming along pretty well. You're piling up the forms in a way that clearly establishes how they interact with one another in 3D space, and are developing a good illusion of gravity in how they slump over one another. One thing to keep in mind however is that right now you're drawing the forms so they feel somewhat more... limp. Try and imagine that these are filled water balloons you're piling on top of one another. While they'll bend to wrap gently around the form beneath them, they're not going to seek to ooze into each little crack and crevasse beneath them.

So! All in all your work is coming along pretty well. I'll go ahead and mark this lesson as complete.