Starting with your organic intersections, you're doing a pretty great job here of demonstrating your understanding of how these forms interact with one another - both in how the sausages slump and sag over each other under the weight of gravity, but also in how the shadows define the relationship between the forms and the surfaces upon which said shadows are cast.

Continuing onto your animal constructions, as a whole you're doing a pretty great job. I can see that there's a great deal of care and thought put into figuring out how your forms individually exist in three dimensions as solid entities (rather than just as shapes on a flat page), as well as how those forms relate to one another within that space. You're also showing a lot of patience with observing your references, doing so consistently and constantly to limit how much you end up relying on your memory.

While there are a few little issues I'm going to call out, as a whole you've done very well and should certainly be proud of yourself.

The first issue I noticed across the majority of your drawings was that you have a tendency to overuse contour lines. Every mark we employ throughout our constructions serves a purpose, and while a tool or technique may itself be a useful one, that doesn't mean it's always necessary, and that more of it is always going to be better. It comes back to the ghosting method - the first step is the planning phase where we determine first what a mark is meant to achieve for us, how it can be drawn to best achieve that goal, and whether another mark actually accomplishes that task already.

If we just blindly pile on contour lines without thinking about it, then we'll end up with far more than we need, with the majority of them not actually contributing anything more to the construction. There's also a greater tendency in that situation to draw them somewhat half-heartedly, not actually designing those contour lines to wrap around the structure.

Long story short - make sure you're taking your time and thinking through every mark you draw. it's really easy to end up just letting your arm take charge, and to put marks that aren't needed. Generally speaking, contour lines themselves suffer from diminishing returns - adding one to a form may have more impact, the second will have less, and the third even less.

The other sort of contour line - the ones that define the relationships between different forms in 3D space, as introduced in the lesson 2 form intersections exercise - are actually much more effective and avoid this pitfall altogether, because only one intersection line exists between two forms. If you focus most of your attention on using them, on defining the relationships/intersections between forms, you'll be able to avoid needing additional contour lines in most circumstances.

Continuing on, one thing I noticed was that while you employed additional masses well in a lot of cases (that is to say, you constructed them as separate, complete forms of their own, defining how they wrapped around the existing structures, etc.) you did have a number of areas where you allowed yourself to take certain shortcuts and alter the silhouettes of forms you'd already constructed. For example, in the second tiger on this page, you added a bump on the back, and one for the belly, just by redrawing that edge rather than introducing a whole new edge.

Altering silhouettes of forms is a manner of drawing that reminds us that we're working on a flat piece of paper - it risks undermining the illusion that we're working with solid forms in 3D space, and it can really hinder the core of everything we're doing here - to create the impression both for the viewer, and for ourselves, that we're looking at something real and 3D.

The best way to see how this happens is to look at what happens when we cut back into the silhouette of a form - the same thing applies when making any kinds of alterations to our existing forms' silhouettes.

So, make sure that you're always building up your construction in 3D space, through the introduction of complete, solid, three dimensional structures. Avoid taking shortcuts.

Aside from that, you're doing really well and are showing a lot of thought as to how your constructions sit in 3D space, and are made up of simpler 3D forms. I'll go ahead and mark this lesson as complete, so keep up the great work.