Honestly, the fact that you freehanded the ellipses is... pretty shocking. I didn't look too closely at first, and just assumed that you'd used an ellipse guide. Generally when students freehand the ellipses for their wheels, they tend to come out a lot rougher. Of course, upon closer inspection your ellipses are obviously not perfect, but they're still coming along very well.

As a whole, you've done a good job of handling the construction of your drawings, both in terms of the structure of the wheels themselves, as well as the rims/spokes that you constructed within them. I can also see that you did try a few strategies for capturing the texture of the tire treads themselves, showing that you were consciously thinking about the concepts from lesson 2. Most notably, you jumped whole-hog into working with filled areas of solid black for wheels 23 and 24, which were definitely a push in the right direction, focusing on attempting to imply the textural forms, whereas in many other cases you did rely more on lines, resulting in a more explicit approach to capture those marks.

Now 23 and 24 were definitely a big move in the right direction, but there's one main issue that could be improved upon. From what I can see, it looks like here you ended up filling in the side planes of your big chunky tire tread forms with solid black. As shown here, there are two main things that can improve upon this:

• Firstly, make sure that the silhouette of each textural form doesn't just focus on the "top" plane of the form. By including strategic corners in this silhouette shape, we can imply the presence of side planes as well, without having to fill them in with black.

• Secondly, focus the filled area of solid black only on the cast shadows themselves - that is, having that filled shape capture the relationship between the form itself (represented by the empty silhouette) and the surface upon which the shadow is being cast.

This approach allows us the greatest flexibility.One example I like to provide to help push this idea actually isn't a tire tread, but it mimics a lot of the same principles. Take a look at this bush viper scale example. This is in a lot of ways quite similar to your approach, but each individual textural form is implied - none of them are actually drawn directly, but rather their presence is suggested by the absence of any explicit linework.

All in all, your work is definitely coming along quite well, and again I'm very pleased with how your ellipses are coming along. Now I do think there is still value in using an ellipse guide for lesson 7 (even the smaller "master ellipse" templates which most students use). Despite their limitation in overall scale, they can simplify certain issues and take an amount of heavy lifting off your shoulders, so you can instead focus on the specific challenges of the lesson itself. It's all about using the right tool for the job to ensure that your brainpower is appropriately devoted to the most important tasks.

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