Starting with your arrows, you're doing a great job in both drawing your arrows with the kind of flow and enthusiasm that really explodes through the space in which they exist, and in applying perspective in a consistent manner to both the width of the arrows as well as the spacing between their zigzagging sections.

Moving onto your organic forms with contour lines, you're largely doing a good job of sticking to the characteristics of the "simple sausage" (two equally sized spheres connected by a tube of consistent width), though there are deviations that you should focus on in the future. Specifically, you have a tendency to have ends that aren't entirely spherical, which throws off the shape somewhat.

Also, there are many cases where the degree of your ellipses - that is, their width - does not change in a natural fashion. In some cases you've got them entirely consistent, in others they seem to change somewhat correctly, but otherwise don't entirely suggest that you understand how they're meant to behave. The degree of a given ellipse tells us of how that particular cross-section is oriented relative to the direction the viewer is looking. As shown here, this changes from location to location, and so as we move along the length of the sausage form, the contour ellipses/curves will widen or narrow accordingly.

Moving onto your texture analyses, I think as you progress through this exercise, you clearly demonstrate a gradual shift from not quite grasping what the exercise is asking of you, to having a very firm grip upon it. In your first row, you're still outlining each scale in its entirety before thinking about the shadows those forms would cast on their neighbours. In your second row, you start thinking about the clusters of forms, but are still somewhat clumsy in your handling - you are however no longer relying on outlines, which is a big move in the right direction. Finally in your last row, you're hitting the nail right on the head. You're demonstrating an incredible attention to detail when it comes to observing your reference, as well as really grasping just how to control the density of your textures. I'm actually quite shocked at the fact that you've pulled off a texture that requires you to go super dark and super light over and over, and that you've still maintained focus on the idea of detail density rather than just "lots of ink here, very little ink over there". Extremely well done. This continues nicely into your dissections exercise, where you apply the same principles as you wrap those textures around rounded forms.

Jumping into the form intersections, you've got a pretty good handle on drawing forms that feel consistent and cohesive within the same space, which is what the primary focus of this exercise is all about. One thing I did notice however was that you have a tendency to approach things using an underdrawing/clean-up pass sort of process that I specifically mentioned you should not be using in the video for this exercise. That applies to Drawabox as a whole - I don't want you thinking as though you put some marks down that would be erased if they could. You need to treat every single stroke as being part of the final drawing. You may add line weight to your drawing afterwards, but that is a process that emphasizes an existing lines, rather than seeking to replace it. The reason this is a problem is that it causes us to trace - a process that overfocuses on how the lines sit on the flat page, and makes us forget that we're drawing edges that flow through three dimensions.

If you want to go back over things with line weight to clarify certain overlaps, make sure you only apply that line weight to the specific areas where it is required, otherwise allowing it to blend back into the existing linework.

With that out of the way, I do want to mention that while this exercise is only meant to introduce students to the challenges of understanding spatial relationships through the intersection lines, you're demonstrating a solid grasp of how they work, and put yourself at a considerable advantage. This is something we're going to be continuing to explore and develop through the rest of this course as we get into constructional drawing.

Last of all, your organic intersections are doing a great job of conveying how the forms slump and sag against one another, interacting in three dimensions rather than just as shapes piled upon one another on the page. Admittedly the contour curves themselves are drawn a little lazily, but the silhouettes of each form goes a long way to sell the illusion.

All in all you've got a few things to keep an eye on, but you're doing quite well. As such, I'll go ahead and mark this lesson as complete.