Jumping right in with your cylinders around arbitrary minor axes, I can see that you're drawing your ellipses confidently, your side edges are fairly straight and smooth, and that you do have a good bit of variety when it comes to the rates of foreshortening used. There are however a couple quick things I want to make sure you're aware of going forward:

• For cases like number 85, where you have the side edges basically running parallel to one another (or more importantly, when you actively try to make them parallel on the page), remember that this only occurs when the cylinder itself runs perpendicularly to the viewer, not slanting towards or away from them through the depth of the scene. This is a very specific circumstance that results in that vanishing point "going to infinity", and given that we're rotating our cylinders freely and randomly here, we can pretty much assume that we wouldn't end up with such perfect alignment. As such, it's best to always incorporate some convergence, even if only very slight and gradual.

• It appears you did not follow the instructions for marking out the "true" minor axis lines correctly. You are drawing a single line for both ellipses, where the instructions have you identify each ellipse's minor axis separately, as there is no reason to assume that they've been drawn such that they align to one another. I'm not going to hold you back on this front, but it is a pretty significant instruction to miss. Make sure that you review it and understand it going forward.

Continuing onto the cylinders in boxes, I did catch some instances of that first point (drawing lines too parallel) towards the beginning, but fortunately you corrected this on your own pretty quickly.

Aside from that early hiccup, you're actually handling this one very well. 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.

You're fairly consistently applying your line extensions correctly (except for cases like number 5 early on where you extended the blue lines in the wrong direction), and as a whole I feel confident that you're analyzing the results of those extensions to better approach the next page. Your well developed grasp of what proportions to choose for your boxes regardless of how they're oriented in space will come in handy as you move into the next lesson.

So! I'll go ahead and mark this challenge as complete - just make sure that when you practice the cylinders around arbitrary minor axes exercise in the future, that you check both ellipses independently, rather than drawing a "best fit" line that goes through both, but doesn't actually identify either one's minor axis as specifically as it should.