Starting with your form intersections, overall you're progressing well, but there are still some little issues when you're dealing with curved surfaces, as I've marked out here. That's pretty normal - at this stage I'd expect students to be much more comfortable with the intersections between straight/flat surfaces, but to still be a little unsure when it comes to the curved ones. Fortunately, since you've had much more mileage with generally thinking about the relationships between forms, I have a diagram that can help a little more. Previously in Lesson 2, it may have been a bit too much to worry about.

One reason this diagram may be beneficial is due to the box-sphere intersection towards the lower right which I'd corrected, where you had the curves reversed. As shown in the diagram, it helps to think about the individual cross-sections of the sphere that are relevant. All we're really doing wiht any intersection is tracing along the surface of the forms - and so considering the cross-sections can help us to break the intersections into pieces, and stitch them back together.

Continuing onto your object constructions, overall you've done quite well - although I do know of one thing that could have improved your results even further, and we'll talk about that in a moment. Before that however, it's important to define exactly why you've done well, or rather what it is you've done so well. It all comes down to the core focus of this lesson, which is about building our objects with a heavy focus on precision. In the last few lessons, we haven't really worked too precisely, rather we've built our objects up one step at a time, dealing with whatever we'd drawn in the previous stage and however it ultimately turned out, rather than thinking ahead. So for example, we might end up with the torso of an animal being too long, but no big deal. It'll just end up being a long individual of that species.

Precision is often conflated with accuracy, but they're actually two different things (at least insofar as I use the terms here). Where accuracy speaks to how close you were to executing the mark you intended to, precision actually has nothing to do with putting the mark down on the page. It's about the steps you take beforehand to declare those intentions.

So for example, if we look at the ghosting method, when going through the planning phase of a straight line, we can place a start/end point down. This increases the precision of our drawing, by declaring what we intend to do. From there the mark may miss those points, or it may nail them, it may overshoot, or whatever else - but prior to any of that, we have declared our intent, explaining our thought process, and in so doing, ensuring that we ourselves are acting on that clearly defined intent, rather than just putting marks down and then figuring things out as we go. Applying it to the example of the animal, to have approached it with precision, we'd have figured out what our intention was for the length of that animal's torso ahead of time - but that kind of approach isn't really that great for organic things.

In our constructions here, we build up precision primarily through the use of the subdivisions. These allow us to meaningfully study the proportions of our intended object in two dimensions with an orthographic study, then apply those same proportions to the object in three dimensions. And so, in applying those subdivisions as fastidiously as you have, you've ensured that each action is the result of preplanning and consideration. Everything was a decision, nothing was left to the whims of chance.

So, what could you do better? Well, in this lesson we're allowed to use rulers, and either you're exceptionally good at executing straight lines, or you made the right call and used one. But there's actually an added benefit to using a ruler beyond simply making straight lines. A ruler allows you to see in which direction your line will extend, without ever having to commit to the stroke. In this, it allows us to judge how the line we're about to draw will converge with other existing lines. Basically it allows us to get better, more consistent convergences in our box forms, or in our parallel edges, if we take advantage of it. That really just means time - taking the time to think about how our lines converge, and taking the time to test each new mark's orientation against the ones that are already present, and adjusting its trajectory as needed.

That is something you would have benefited from a great deal. As a whole, the only real shortcoming in your drawings is that the convergences are not great. This of course is something that would benefit from practicing the kinds of freely rotated boxes (with line extensions) from the box challenge, but it is also definitely something that could have been reduced given the use of the ruler.

But fortunately, that's really the only shortcoming. The rest of your constructions are well put together, you're approaching everything in steps, and your decisions largely have been predetermined, then acted upon, rather than being made on the spot and reacted to. So! I'll go ahead and mark this lesson as complete.