Congrats on completing the wheel challenge! I'll do my best to give you useful feedback so that you can improve.

Starting with the structural aspect of your wheels, you've generally done a good job in terms of building out your wheels with successive ellipses. You've correctly included a gentle arcing to the profile of the wheel (with smaller ellipses on the outer sides, helping to convey that the tire itself is inflated, and would land with a bounce rather than a solid thunk. However I feel like this could have been pushed a little further on a couple of wheels such as 2, 11 and 12 but if it was an intentional choice to leave them more elongated then that's fine.

You've also done a great job with the spokes and rims by making sure to include a side plane for the spokes. However you have used form shading on wheels such as 23 and 8 to define the side planes which is something that should be avoided in this course.

For the textural component of the challenge you've fallen into the trap of explicit markmaking. You've got wheels (9, 3 , 5) where you just outlined the textural forms just as you would any other form, applying explicit markmaking across the board. This puts us in dangerous territory when our wheel becomes part of a larger scene, becoming an unintentional focal point, and drawing the viewer's eye whether you want it to or not.

Then you've got the ones where you filled in the side planes of those textural forms, like in 13, 12, and 2. This unfortunately is more akin to form shading, where the side plane is either lighter or darker based on its orientation in space. Cast shadows are actually a new shape designed based on the relationship between the form casting it and the surface receiving it - as opposed to an existing plane/shape that is merely being filled in. The thing is, they can look very similar. This diagram helps to clearly show the difference between the two.

Finally you also end up filling in the grooves with black (11, 7). The reason this is wrong is because we end up focusing on the thing we can name which would be the groove / crack as the form instead of the cast shadow from the walls which is what we should be drawing. This subtle difference in what it is we are drawing may not even look different it could even just end up looking exactly the same, but the difference lies in how we think about the marks we are making.

Lastly, I wanted to give you a couple additional diagrams - more focused on how we think through the texture analysis exercise in Lesson 2 - but still applicable here since it's all about understanding how to approach identifying our forms without drawing them, so we can imply them with cast shadows alone.

• Firstly, this diagram (or alternatively this one which is essentially the same, just framed a little differently in case it makes more sense) demonstrates how texture requires us to think about the relationship between the light source and each individual form.

• And secondly, this diagram shows, using a texture of melted wax, how we can think about first identifying the forms themselves, and then designing the shadows they'll cast.

Anyway! As I mentioned, the "trap" aspect of this challenge is very much by design - so I'll still be marking this challenge as complete. Just be sure to review the texture material, especially these notes.