Jumping right in with your cylinders around arbitrary minor axes, your work here is in many ways well done. You're drawing your ellipses and straight edges with confidence, maintaining even shapes and smooth trajectories which continue to improve over the set. I can also see that you did strive to incorporate a variety of rates of foreshortening through much of this section, although from about 120 to 150, you seemed to stop and fall into the pattern of drawing cylinders with no foreshortening at all.

This - that is, drawing those side edges as parallel on the page without any convergence as they gradually recede from the viewer - is actually incorrect. Reason being, you're effectively trying to artificially force the vanishing point to infinity, but this is not something that is strictly within our control. What we do control is our intended orientation for the form itself, and it's that orientation (or rather the orientation of the relevant edges in 3D space) that determines where the vanishing points go.

A vanishing point goes to infinity only in a very limited set of circumstances - it requires the edges it governs to run perpendicular to the viewer's angle of sight, not slanting towards or away from them through the depth of the scene. Given that this challenge, like the box challenge, has us drawing forms that are freely rotated in space, we can pretty much guarantee that our cylinders wouldn't really align quite so perfectly. This means that there should always be some convergence to those lines, even if it's only very slight and gradual.

Continuing onto your cylinders in boxes, 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.

Unfortunately, from what I can see you may have misunderstood how to actually approach those line extensions, specifically in terms of how to apply the "contact point" lines. Currently you appear to be drawing lines from one ellipse's contact point, down the length of the cylinder through the other ellipse's corresponding contact point, and onwards. That is not what is depicted in the instructions.

Instead, as shown here on one of your cylinders, each ellipse has its own separate contact point lines - they are not shared between ellipses. They are also extended towards each of the other vanishing points, rather than having all our lines extend towards one.

I suspect that you may not have reviewed the instructions carefully enough, then pushed forward without double checking. That's unfortunate, as it will require some revisions to confirm your understanding of the concept. I won't be going overboard with this, as the rest of your work for this part of the challenge is reasonably well done.

You'll find the revisions assigned below.