The issue isn't with your ability to do the exercise - the issue is that you are deviating from the instructions in regard to focusing only on doing the best of which you are currently able when completing the assigned number of pages, based on what you're able to understand from the material and your current skills, and moving on. Then, when the lesson's homework is completed in full, letting the person giving you feedback decide whether you missed something relevant to what you should be grasping right now, or whether you're good to continue forwards and integrate the exercise into your regular warmups.

Drawabox as a course focuses above all else on one concept - spatial reasoning. That is, developing students' ability to understand how the marks they make on a flat page actually conveys information that exists in 3D space. That also happens to be exactly what this exercise relies heavily upon, which is why we stress throughout the lesson material that it is not something you're going to "get" right now.

Rather, we introduce the exercise here so it helps to define the way in which you approach the constructional drawing exercises we do from lessons 3-7, where we're repeatedly drawing forms as they sit in 3D space and considering the relationships between them within that space as we combine them to create more complex objects. That in turn helps to develop the underlying spatial reasoning skills, which also changes the way in which you look at the form intersections.

Then, in Lessons 6 and 7 both, we assign the exercise again because it is at that point that the student is in a position to better understand any further information we may be able to provide on that front, based on where your remaining areas of difficulty may be.

It is largely the same as with the texture material, which also relies on the same understanding of spatial relationships in order to design cast shadow shapes that convey the relationship between the textural form casting the shadow and the surface receiving it. These are exercises and concepts we introduce now so they provide context to how the elements we explore later are considered, with that then feeding back into these more specific applications of the concepts.

When, however, we get overly caught up in a specific exercise, we become prone to hyperfixating on one thing, to the detriment of the whole. The whole being, of course, the manner in which the course is designed to be used.

Long story short, don't worry about it - keep focusing on following the course as instructed, and accept that some things will come up with no expectation that the student is "ready" to tackle them successfully. What matters most in learning is the process, not the end result of any given exercise.

I just wanted to add a small point about the confusion your brain is having when you try this exercise. The biggest revelation for me was when I realized that the boxes don't actually have a "correct" configuration. Here is a quick example I did. I first did the two center boxes at 1 with no indication of how they intersect. Then I photocopied it four times and indicated the intersection four different ways with pictures 2-5. I started with the exact same two boxes but got four different configurations. All of them are "correct" simultaneously. This is why your brain freaks out. It can see all the possibilities. I think this is because we are drawing something abstract where size and distance are not determined by the object itself. There is no external reference. If you drew two people and one was significantly smaller and overlapped by another person, your brain would instinctively know which was forward and which was back. With this exercise, you are making the decision as to which configuration your going to show. My advice is to start with deciding on a single line of intersection. After that, the other lines are mostly predetermined. For example, in picture 4 I emphasized the top line of the box on the left. This then led to other lines emphasized and I ended up with what I ended up with. All the boxes started with a decision of which box would be forward, back or partially covered. Hope this helps.