Starting with the organic intersections, these are generally looking very good. The forms slump and sag over one another with a believable sense of gravity. What's more is that your lines are drawn with a sense of confidence, ghosting before making each mark. All in all, I have no problems with how you approached these. Good job.

Moving onto the animal constructions, these are done equally as well. The lines here are just as confident and there is clear attention being put into your general construction and showing an understanding of the relationships that exist between your different forms, and defining them clearly. There's no instances where you're working in 2d space - that is the addition of partial shapes or one off lines. Everything is introduced through a new complete, self enclosed form. There are a few things I'd like to bring up but these are but minor things.

I am definitely pleased that you're using additional masses a great deal, layering them together, and building upon them bit by bit, rather than creating single masses that take on too much and become too complex, all without having the need to slap in too many superfluous contour lines. While the masses themselves are on the right track, there are still ways you can push these further as shown here. Look for opportunities to push these masses into other forms to make the construction feel more grounded and give us clear places to use inward curves and sharp edges.

You're definitely off to a great start in the use of the additional masses along your leg structures, but this can be pushed harder. A lot of them primarily focus on the silhouette of the leg without as much consideration for the forms that don't directly impact it. There's value in exploring these inner masses - like a missing puzzle piece that helps hold together the ones that create bumps along the silhouette's edge. Here's an example from the dog's leg demo, as you can see, there's blocked out masses along the masses including the one fitting in between them all, even though it doesn't influence the silhouette. Thinking about it this way will help your further push the value of constructional exercises and puzzles.

I do like how you're approaching your feet. Corners are a good idea since they help imply the presence of internal planes and generally to make these structures feel more three dimensional. I do notice you going for boxier forms but I do think following the approach shown here from another student's work would help you push this even more. Try to push for adding other boxy forms for toes and such.

Lastly onto head construction, it seems like you're following the head contrution demos closely, and as a result much of your heads are coming along quite nicely. There are ways to push the constructional exercises harder.

One great example of this in on the camel you drew. Compared to the other contructions, the camel does feel quite a bit simpler and looking at other references, it can be a bit difficult to fit into the head construction approach shown here. The trick really comes down to making a number of smaller moves, one at a time, rather than trying to make a few big moves that capture a lot of things at once. For example, starting off with a smaller cranial ball allows us to start establishing structure, without being committed to a scale thay may not work properly. Drawing a huge cranial ball is a common mistake, resulting with the rest of the facial features being smushed down in comparison.

So be sure to start small and build up slowly with small, individual pieces and look back at your reference to see what it is you're trying to capture. Here's an example from the banana-headed rhinoceros. We're still starting with the same components but get into some unique case driven actions towards the end, especially the extra bulk in the back of the head.

And that about covers everyting I have to say. You're doing very well as a whole and working more on observation would help take a strong construction and produce even more believable constructions. I'll be marking this as complete but be sure to look over the points i've raised moving forward.