Starting with your cylinders around arbitrary minor axes, your work here as it relates to the core focus of the challenge is coming along well. You're checking your minor axis alignments fastidiously and identifying both large and small discrepancies (the latter is especially good, as it's easy to miss smaller mistakes and end up plateauing as a result), and you're executing your ellipses with a lot of confidence, which helps to keep them smooth and evenly shaped.

My biggest concern comes down to the linework - specifically your straight lines, used for the side edges of the cylinder. It appears to me that here you've neglected to adhere to the steps of the ghosting method, and may have either skipped or reduced the time investment in the planning and preparation phases. Often when students neglect those first two stages, they'll end up taking more time in the execution of their marks, leading to hesitation and a distinctly less confident stroke. So, always remember - the ghosting method should be employed in its entirety throughout the course. While the long term intent is for it to develop unshakeable habits in how you naturally approach making marks (taking a moment to think through the nature of the mark you want to make), that will only be achieved by having students be especially intentional in its use throughout the work they do for this course.

Carring over into your cylinders in boxes, your work here is done quite well. You've paid attention to the instructions and applied them correctly. This exercise is really all about helping develop students' understanding of how to construct boxes which feature two opposite faces which are proportionally square, regardless of how the form is oriented in space. We do this not by memorizing every possible configuration, but rather by continuing to develop your subconscious understanding of space through repetition, and through analysis (by way of the line extensions).

Where the box challenge's line extensions helped to develop a stronger sense of how to achieve more consistent convergences in our lines, here we add three more lines for each ellipse: the minor axis, and the two contact point lines. In checking how far off these are from converging towards the box's own vanishing points, we can see how far off we were from having the ellipse represent a circle in 3D space, and in turn how far off we were from having the plane that encloses it from representing a square.

In applying the line extensions as fastidiously and thoroughly as you have, you've armed yourself after each page with a clear analysis of where your approach can be adjusted to bring those line extensions' convergences together. Thus, though it likely wasn't foremost in your mind, we were sneakily developing your understanding of how those proportions hold in 3D space, and your ability to judge them for yourself has certainly developed nicely. There is of course room for continued growth, as there always is, but you should be well equipped to apply what you've learned here into the next lesson.

I'll go ahead and mark this challenge as complete.