Starting with your form intersections, these are generally looking quite well done. There are some hiccups in how you handle curving surfaces, but you're constructing the forms themselves very well, and there are many aspects to your intersections that suggest a strong, well developing understanding of the relationships between these forms. I've marked out some of the curving intersection issues here. You frequently have a tendency to treat a curving surface as though it were straight for the purposes of your intersection.

Moving onto your object constructions, there are definite strengths here but there is one choice you appear to have made that has definitely held you back a fair bit: you seem to have been freehanding all of your linework. In this section at the beginning of the lesson I specifically recommend that students use things like rulers in order to put the student's focus on where they're intending for their lines to fall, rather than their ability to draw them in precisely the right place. Up until this point, the material has students contend with both, largely because the nature of organic construction is much more forgiving than geometric construction like this. When I make certain recommendations, there's a reason for it, and it is (as in this case) laid out for you.

There are obviously circumstances where getting an ellipse guide is going to be difficult (most students pick up a master template, which has a range of ellipses at different degrees, but limited to just a few relatively small sizes, since getting a full set of guides is expensive). Getting some form of straight edge with which to draw is pretty straight forward though, to the point that you could make one out of a piece of paper if necessary.

Anyway, I'm going to do the rest of the critique setting aside any issues with linework. Honestly, your linework is often pretty good, with the odd one that wavers a little.

So what stands out to be first and foremost is that you appear to struggle a fair bit with your initial box constructions. Given that they establish the framework that will support the entirety of your construction, any mistakes in the initial box will inevitably interfere with the construction as a whole. This first hit your two barrel attempts pretty heavily, especially when you had to position two separate boxes relative to one another. The most important thing here is that when drawing any line, you always need to consider the lines it's meant to run parallel with. Find them, and think about how they're extending off into the distance, and how you can orient this next line in such a way that it's going to converge consistently with the others. Your barrel's "stand" box (the lower one) in both cases had lines that definitely converged differently than the major lines of your barrel, which put you in a pretty difficult position to start.

Your computer mice - especially the second one - improved on this quite a bit more. Your box's discrepancies are much more minor, which shows that you were thinking much more about the lines as you laid them out. Your use of subdivision, and laying out the various orthographic shapes also seems to have gone quite well.

A quick note about this clock. I mentioned in the lesson that you should only use one kind of pen for the whole drawing - don't do your construction in one pen and then attempt to do a clean-up pass in another.

Moving forward through the work, I think overall you demonstrate a good grasp of how to subdivide and plot out the various complex elements of your constructions. There are definitely some places where you adhere more loosely to the structure/scaffolding you lay out however - for example if we look at the curvature of the mouthwash bottle, we can see it zigzagging across the straight line of the main box that was used to contain it. As shown here, having additional structure in place and building your curving portions such that they actually adhere to this structure (rather than loosely zigzagging around them) would result in a much stronger resulting object.

This sort of looser adherence to construction and perhaps an inclination to lay out less of the construction than you had in previous drawings definitely interfered with your last two drawings as well (the toaster and electric toothbrush). All in all, I know you can employ this kind of construction well, but I think that there may be circumstances where you weigh whether or not something is really necessary. You try and judge whether or not you can jump a gap instead of building a bridge across it. In this lesson, what I really want to see is you bridging even the smallest gap, in order to learn how to be as specific as possible.

So! All in all your work is ultimately showing a good deal of growth, but I'm going to ask for one more drawing - just one more - investing as much as you can into each individual element you add into your construction to ensure that everything is built out with precision. Do as much subdivision as you need, don't approximate anything. And use a ruler.