All in all your work here is very well done. Starting with your cylinders around arbitrary minor axes, while it would have helped to have the minor axes drawn in a different colour (during the analysis phase), you've drawn your marks with confident, consistent strokes. You do have a bit of a tendency to overshoot your side edges (it's normal for the minor axes but those would, at this point in the course, generally show a little more control - if you're struggling with overshooting lines, you may want to try lifting your pen when you hit the end point instead of slowing to a stop) but the ellipses are smooth and consistent, and your lines are straight. It's probably for the best that you stopped trying to add line weight, as it wasn't really helping much in the context of this exercise.

It is admittedly worth mentioning that the hatching is a little sloppy. Whenever you add hatching, it should go from edge to edge and stop, rather than being allowed to spill over as freely as you've done here. That goes doubly when it is something you decide to add to a drawing, rather than something that is explicitly part of the exercise instructions.

The main thing - after line quality, the care with which one checks their minor axes, etc - I look for in this part of the exercise is whether the student understands how the shift in scale and the shift in degree between the ellipses on either end relate to one another, and for all intents and purposes here you appear to grasp that fairly well. Basically it comes down to the fact that when the far end is much smaller than the closer end, it suggests that there's a good bit of distance between them - that the cylinder is longer. And similarly, when the far end is much wider than the closer end, it means the same thing. So there shouldn't be any situations where there's a significant shift in scale, and a very little shift in degree, or vice-versa, as this suggests that the cylinder is both long and short, depending on which features you're looking at.

I did find a couple cases of this - like cylinder 102, and 106 - but they were pretty minor all things considered. I did however see some cases as well where the near end was visibly wider than the farther end (like 103, which you marked with a little X so I assume you were aware).

Moving onto the cylinders in boxes, these are actually on a whole different level when it comes to the confidence demonstrated in the linework, and the solidity of the forms. Your lines are rich and dark, and your boxes are very solid. The convergences of your box's lines show a good deal of consistency, which suggest that you have been keeping on top of these exercises since completing the box challenge.

This exercise focuses primarily in improving students' instincts when it comes to drawing boxes that are proportionally square on two opposite faces. We do this using the same approach as the box challenge, where the line extensions tell us where we're off so we can make small adjustments to improve on those convergences. In this case we add to the lines those from the ellipses - the minor axis, the two lines defined by the contact points. These lines align to the box's vanishing points only when the given ellipse represents a circle in 3D space that is resting on the surface of one of the box's faces. If that ellipse therefore represents a true circle, then the plane enclosing it also must represent a square in 3D space. If the lines are off however, and we make adjustments to bring them more in line in the next attempt, we're gradually training ourselves to better eyeball those correct proportions. In this regard I think you've shown a good deal of growth and development that will serve you well in the next lesson.

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