Alrighty! Starting with your arrows, these are doing a great job of flowing fluidly through space. One thing to keep in mind though is that as the far end of your arrow's ribbon gets really narrow, that tells us that it's getting very far away from the viewer. This also means that the distances around it - for example, the distances between the zigzagging sections - should also be compressing at the same rate. While in many of these you are indeed compressing that space, this can definitely be pushed further to achieve a more natural sense of depth in the scene.

Moving onto your organic forms with contour lines, you've largely done a great job. Your organic forms are all sticking to the characteristics of 'simple sausages' quite well throughout the exercise, and you're drawing your contour ellipses and contour curves confidently, but with proper use of the ghosting method to achieve accuracy and control. There's only one thing I want to draw to your attention - right now your contour lines are all roughly of a consistent degree across the entire length of a sausage. The degree of your contour line represents the orientation of that cross-section in space, relative to the angle the viewer is looking, and as we slide along a given form, these cross-sections are going to open up to be more visible, or get narrower and become less so. This is demonstrated here. Basically it just means your contour lines should be getting narrower/wider as we slide along the form.

Moving onto your texture analyses, this is exactly what I want to see. You're completely dealing in shadow shapes, with no individual lines or outlines whatsoever, and you're doing a great job of identifying the actual forms present in your textures, and deriving the shadow shapes from their relationships with their surrounding surfaces. This is spot on, and I'm very pleased with how you're able to apply those principles to achieve considerable control over the density of your gradients.

While your dissections are still looking good, there is an element of this which is lost when you move onto this next exercise. Specifically, it's the fact that when you've got textures made up of individual, discrete textural forms, you fall back on outlining them first, then figuring out your shadow shapes, whereas in your texture analysis exercise, you were jumping into the shadow shapes from the get-go. It's definitely a lot more difficult to jump right into shadow shapes, especially when we start leaning more heavily on observing our reference more carefully (the brain can only handle so much), but when tackling this sort of thing in the future, try to make a point of setting lines aside altogether.

For your form intersections, I'm very pleased to see that despite the complicated nature of this exercise, you're still holding true to the core principles of mark making, applying the ghosting method consistently throughout and thinking about how each box is constructed with a mind to the convergences of your parallel lines. You're doing a great job, as a result, of constructing these forms such that they feel cohesive and consistent within the same space.

The only thing I'm noticing obvious struggling with are the more circular ellipses required when drawing a sphere - that is definitely something you'll want to work on. Often times when those spheres get uneven or misshapen, it occurs because we slip back to drawing from the elbow, which doesn't quite have the appropriate range. Practice, of course, is also a factor.

As for the intersections, you've got a great start with these. The intersection lines themselves are, as a component of this exercise, an introduction to thinking about how forms relate to one another in 3D space. This is at the core of Drawabox as a whole, and I don't expect students to have any experience with it prior to this point. Having planted the seed here, we'll continue exploring this a variety of ways throughout the course.

Lastly, your organic intersections are looking great. You've done a good job of capturing their interactions as they occur in 3D space, rather than stacking shapes on a flat page. You're also selling a strong illusion of gravity in how the forms slump and sag over one another.

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