Nicely done! You've demonstrated a great deal of patience nad care in planning out every individual stroke and executing them with confidence to ensure smooth, straight, accurate lines and ellipses that come out smooth and evenly shaped. You've also done an excellent job of identifying the "true" minor axes of your ellipses after the fact, and over the course of this first section of the challenge it has definitely served to reduce your margin of error, bringing many of your ellipses more closely in line with your intended orientation.

One thing I did feel that was a little lacking, and that you could focus on in the future when practicing these on your own is to vary the use of foreshortening on your cylinders. Here we're primarily seeing cylinders that have very shallow foreshortening applied to them, resulting in minimal changes to both the ellipses' degrees and overall scale when moving from the end closer to the viewer to the end that is farther away.

One thing I was giving students room to explore on their own is the relationship between these two kinds of shift - that of degree, and that of scale. As often students learn better when allowed to come to certain conclusions on their own, I give them a the opportunity to pick up on these kinds of relationships on their own, but I do feel that since you didn't get into much more dramatic foreshortening, that opportunity was missed here.

The relationship in question is that both the shift in degree and the shift in scale are properties of foreshortening. If the far end is much farther away than the closer end (suggesting that the cylinder itself is longer), we tend to see both a greater shift in degree (the far end will get much wider, proportionally speaking) and a greater shift in scale (the far end will be overall smaller). This also means the opposite is true - if the cylinder itself is short with shallow foreshortening applied to it, you'd get minimal shifts in both cases.

Ultimately the conclusion to be drawn is that we won't see cases where we get a dramatic shift in one, but not in the other, since these would suggest contradictory things. We won't see a dramatic shift in degree but a minimal shift in scale, or vice versa. While there weren't many cases to explore this in the work you did for the first section of this challenge, do keep it in mind for the future.

Moving onto the cylinders in boxes, one thing caught my eye - because you were more focused on getting your ellipses to fit inside of the planes, you kind of dropped the ball in terms of the actual alignment of these ellipses relative to the intended minor axis. As shown here where I marked in the correct minor axes for some of your ellipses, you missed the fact that a lot of them were quite drastically misaligned.

Now, having those minor axes aligned incorrectly is actually not in and of itself a problem. More than anything, it's part of the exercise - but it's critical that you remain aware of it, and actually find those correct minor axes. The reason for this is that this exercise is actually more about the boxes themselves than the cylinders. If you think about how back in the box challenge we use line extensions to help identify whether our boxes' sets of lines are converging consistently towards their shared vanishing points.

In the same way, the cylinder (specifically the ellipses and the resulting minor axis and contact point lines) serves as an extension of that. What this allows us to test is whether or not the box we've drawn has a pair of faces that is proportionally square. When the contact points and minor axis are way awry, it's more likely to be a result of the face's proportions.

Now, while you definitely did slip up on a lot of these minor axes and not quite address this element of the exercise, I feel like pointing it out should be enough to get you back on track. As such, I am still going to mark this lesson as complete with no revisions required - but be sure to continue practicing this sort of thing on your own in order to equip yourself properly for future lessons.