Hey there Grain! Welcome to Drawabox and thanks for your patience! I'm sluggy and I'll be going over your submission today, so let's get at it!

Lines

This is a decently strong start you have here in terms of line flow. Your marks are consistently smooth and confident, which is precisely what we're looking for. However, I will note that there is a great deal of fraying on both sides of your super imposed lines. This tells me that you may be going a touch too quickly, since you're not lining your pen up with the starting point of each line. Likewise, you tend to over or under-shoot your end points.

What you're looking for is a speed at which you're both comfortable, consistent, and accurate. Of course, we don't expect you to be there immediately, but this is what we're shooting for. Slow down a touch and utilize the ghosting technique so that you can achieve smooth lines without going too quickly. Once you have your flow down, go ahead and start using the ghosting technique (and make sure you're rotating the page) to line yourself up with the end-point.

Hitting the end point will be important later to sell the illusion of 3D form on a 2D plane, so it's not to be overlooked! However, you are quickly moving in the right directions, so just keep in mind what I noted here: slow down, and use the ghosting technique to help hone your accuracy!

Ellipses

This is a pretty decent start as well. Your ellipses are fairly confident and you draw through them a good number of times, but they're also a bit loose and don't sit snugly within their alloted spaces. The good news, though is that, just like your lines, you can tighten these up by using the ghosting technique. Your aim is to get ellipses with a confident and even shape, sitting snugly in their planes, tables, and funnels. Drawing through and ghosting will allow you to tighten them up and ghosting will assist you with accuracy.

With your funnels, keep a very close eye on that minor axis. You want your ellipses to be aligned and bisected by this line - consider it like the spine of your funnel. This will be important for later lessons.

Rough Perspective

Looking good here! You keep your verticals perpendicular to the horizon and your horizontals parallel which tells me you know how each line should behave. Likewise, your check lines are fairly accurate, so nice work there.

This is a good point at which to point out how over- under-shooting your end points has the effect of weakening the illusion. It's not too bad here, but this is just to highlight why accuracy is important and what you're ultimately shooting for.

Rotated Boxes

This is a very strong attempt at the challenge. While your line-work is a bit sloppy, the boxes are fairly readable and you've drawn through them nicely as well. The major pitfall here is that you don't maintain consistently sized gaps between each box which leads to unnecessary guesswork. The key thing here is that keeping consistent gaps allows you to measure each box against the previous box, in both positioning and rotation.

Likewise, with your rotation - you get pretty close to the 180 degrees, but to ensure you achieve a fuller rotation next time, keep an eye on the VP. You want to make sure the VP is moving far enough past the VP of the previous box that the box is rotating rather than simply moving back in space. Overall though, this is a strong attempt, nice work!

Organic Perspective

So I will say that your mark-making could use a bit of improvement here (the overshooting is weakning the illusion of 3D form), but overall this is a good start. There's a bit of room for improvement in getting sets of parallel lines to converge evenly towards shared vanishing points, but that's nothing the 250 box won't help with!