Jumping right in with your form intersections, your work here is honestly far and away better than we generally expect for this stage. It's pretty normal for students to be more comfortable with intersections involving flat surfaces, but to still have issues when encountering those that introduce curving surfaces. In your case, I only really found one hiccup (as noted here on your third page). Aside from that one, you handled both flat and curved intersections quite well, suggesting that your spatial reasoning skills have been developing very nicely.

I will provide you with this diagram, not because I think you need it, but because I generally share it with students now, when they're more familiar with the concepts behind intersections to be able to make use of it, and it wouldn't make much sense to deprive you of it if it can add any further insight to your existing understanding.

Continuing onto your object constructions, by and large you've done a great job of allocating your attention to the lesson's core area of focus: precision, and what we can do to increase it in our constructional studies. 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.

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.

You've done a great job of employing those concepts, although I did notice a few places where additional steps could be taken to increase that precision further. For the rubik's cube construction, I noticed that you placed the holes based on a common center point, which is a great start - although it doesn't guarantee that each hole would actually be the same size. To do that, we can use mirroring as shown here (you'd do it in the other direction as well to enclose each diamond in its own space, and would also do this for the other visible faces (although they'd end up lining up making it a little less cumbersome). I also noticed that you used a technique from outside of this course to construct the cube (which I imagine also locked you into a very specific angle). I would recommend sticking to the techniques presented within the course - I know we haven't yet gotten into how we can go about maintaining cubic proportions yet (that is introduced in Lesson 7 as it's quite complex), but that simply means that for your homework here, maintaining proportions across different axes isn't something you'll be dinged for. By sticking to what's in the course, you can ensure that you don't end up getting distracted by other concepts that may focus more on the result, rather than the exercise each constructional drawing is meant to be.

Another point I noticed was how you went about tackling this mug - specifically the handle. Honestly there isn't really anything wrong with how you did it - I can see that you used straight edges which were then later rounded out, to maintain precision throughout. I just wanted to bring to your attention that the section that discusses thise matters regarding curves does have a demo of a mug in it that, while approaching the body of the mug itself less strictly, is much more particular about building up the handle. You may find it useful in comparison to what your approach may have helped with, and where it may have fallen short.

Anyway! All in all, very solid work. I'll go ahead and mark this lesson as complete.