Alrighty! Starting with the structural aspect of your wheels, you are definitely making excellent use of your ellipse guides, and I'm very pleased to see that you did use one. Many students find them to be very limiting, but in terms of helping them focus on the core aspects of this challenge, it's worth the smaller scale we're limited to. You're doing a good job in laying out the ellipses to create a gently curving profile to the wheels, which helps convey the "inflated" nature of the structure, and tells the viewer that if it were to fall, it would land with a bounce rather than a heavy thunk.

When it comes to how you've handled the rims/spokes of your wheels, your results are somewhat more varied - there are places where you do a great job of constructing them fully as we see in cases like wheel 20 where you've built out both the outward face and the side plane for each spoke structure, helping to make them feel more solid and tangible. You've also got cases like 1 and 3 where those structures aren't given a side plane, so they feel more paper-thin. We can see this to a varying degree on some of the later ones too, but in cases like 18 you seem to be somewhat more attentive to at least trying to define those side planes more regularly. Just be sure to keep an eye on that.

There's also cases like the bike wheel in number 2, which is something of a special case. I understand that those spokes are very thin, but in general, I would avoid representing any form with a singular line, because it simply has no capacity to show form. So, in this case I would sooner make them a little too thick (by establishing each spoke with two edges), than leaving it just as a single line.

Continuing onto the textural aspect of this challenge, I can see that you have definitely entered this challenge with a clear awareness of texture as being a relevant part of it. Many students end up forgetting about it altogether, being as far removed from Lesson 2 as we are, and so this challenge serves as a sort of "trap" to give them a rude little reminder that they need to go back and review that material. You certainly are aware of those concepts, and I can see you trying to deal with them in a variety of ways, although this is definitely an area where there is room for improvement. I do however greatly appreciate that you have so clearly put forward a lot of effort to try and deal with texture as noted in the lessons. That goes a lot farther than one might usually think.

Early on - in wheels like number 5 - we can see that you're trying very hard not to put the actual textural forms down, but rather only draw the shadows they would cast. Unfortunately the marks you put down do feel a little... non-specific, but this is still very much moving in the right direction. At the end of the day, understanding each and every textural form, how it sits in space and how it relates to the surfaces around it, is not easy. We're used to defining these forms first, and then having all that information clearly visible in front of us. This makes it a lot harder to hold that information in our heads all at once, and the key to doing that successfully is really about doing so one textural form at a time. A texture may have dozens or even hundreds of textural forms - but that simply means that it's going to take more time to draw correctly, while adhering to what the course requires. So, don't be afraid of things taking longer than you feel they should. It's not a question of doing it quickly, but rather of being patient enough to do it to the best of your current ability.

Now because of that required time investment, it's not abnormal for students to end up doing what you did - falling into something easier, like filling in the actual side planes of the textural forms, rather than the shadows they cast. This allows us to partially define and draw the textural forms in question (giving us something more solid to rely upon), but it's also not really what we're after. We can see this in cases like 24 - although since you didn't draw the textural form entirely (which is a good thing), it's not as obvious that there's a difference between this and what you were doing before.

It helps more to focus on what it means to draw a cast shadow, rather than simply filling in a side plane (which itself is more akin to form shading, which as discussed here is not something we employ in our drawings for this course). So, let's take a step back and look at this in the context of the texture analysis exercise from Lesson 2.

Here's a diagram that takes us step by step through how to think about a texture, in order to draw the gradient from that exercise. First, traced over the image of melted wax, I've identified some of the actual forms at play - individual globs of wax. This is what I'm doing when I'm looking at my reference - I'm identifying each form, one by one, and understanding how they sit in space in relation to one another.

In the row below that, I've represented how I'm thinking about how I might arrange those textural forms in the surface I'm using in my gradient. Remember that if we were to look at this surface from the side, it would not be flat. It would be as seen here (or alternatively here in case this version of the diagram makes more sense). These are not candle-wax specific, but rather just representing how forms are arranged on the surface, and how they relate to the light source, resulting in much longer, deeper shadows the further from the light source we move.

Now, it's with this understanding of how we're arranging these forms upon our surface that we can actually think about all of the individual shadows, one by one. Outlining those cast shadows is very important, because it's this step which allows us to design this shape, whose whole job is to establish the relationship between the textural form, and the surfaces around it. I've faded out the results of the previous row (where I outlined all of the candle wax blobs) - the hard part is that this needs to be done in your head. You can't draw those globs on the page. What you can do however is think about each individual glob one at a time, as though you're adding them in order, and with each one you're defining its cast shadow as you add it. So you're not thinking of every glob simultaneously - just one at a time, and maybe a bit about the ones around it.

And finally at the bottom, we have the actual results - we've filled in our designed shadow shapes, and due to the light source being at the far right, the shadows get deeper moving towards the left, eventually merging into that solid bar on the leftmost edge.

So, texture comes down to thinking about the actual forms at play, and doing so one at a time. Time is important, and if we rush ourselves to go faster than we're able, we simply won't pay attention to each form, one at a time. There is always a lot of temptation to just deal with randomness in this regard, but that's not solving the problem - it's giving up on it instead.

The last thing I wanted to offer you is this diagram. It's pertinent to the tire tread textures where we have a lot of shallow grooves, as most students are prone to thinking about the groove itself as though it's the textural form they're supposed to be thinking about. As shown in the diagram however, it is the walls that surround the grooves/holes which cast shadows upon one another, and upon the floor of the hole itself. This also applies to any texture with holes - so sponges, cracks, etc. Often the difference in the result between understanding the groove to just be empty space, and thinking of the grooves to be the actual form can be negligible - but given that these are all exercises, it still matters a great deal how we think about them.

Now, you needn't worry - I won't be assigning any revisions. It's entirely normal for students to still struggle with applying texture here, and I am very pleased to see that you did not fall back to simply using explicit markmaking, and that you made an effort to apply the implicit markmaking from Lesson 2. So! I'll go ahead and mark this lesson as complete.