Over the course of this lesson, I think you've shown a considerable amount of growth. Earlier on, you definitely approached your duck drawings rather hesitantly - drawing as small as you did wasn't really beneficial (drawing small limits your brain's ability to think through spatial problems and makes it harder for you to engage your whole arm while drawing, resulting in the clumsiness of these two little fellows). As you loosened up however, you definitely started thinking much more about the relationships between the forms in your constructions and how they all fit together, which gradually yielded more solid, believable structures.

Starting with your head constructions, this is an area that you were definitely moving in the right direction throughout the process, but there is definitely room for improvement. Right now you tend to draw your various facial elements with gaps between them. Earlier on, you had more eye sockets floating arbitrarily, but as you progressed, you'd end up with more regular gaps/spacing, like in this calf's head.

It is best to just eliminate those gaps entirely, and to ensure that the eye socket, muzzle, brow ridge, cheekbone, etc. all get wedged together with their boundaries defined. This informal demo, which is linked at the very beginning of the tiger head demo, explains how you should thinking about head construction as a sort of 3D puzzle where all these pieces fit together. Once my overhaul of the course material reaches lesson 5, this is the approach I'm going to be pushing in any new video content regarding head construction. Currently however, the most I can do is say so at the top of the tiger head demo. Be sure to read through it if you haven't - along with the thing about the 3D puzzle, it also explains how we use these various elements of the head to separate our cranial ball's smooth surface into a series of distinct planes. Also, note how I explicitly define how the muzzle connects to the cranial ball.

Moving onto your use of additional masses, I'm quite pleased with how you're considering the way in which these forms wrap around the existing structure. You're designing those silhouettes in specific ways that define clear relationships between the forms. This is often something that students struggle with. The only thing I want to call out here is that when you design those silhouettes, it's always best to think in terms of areas that press against some existing structure taking on complexity like corners and inward curves in response to that contact, and areas that don't touch anything remaining as simple as possible, as shown here. This means that if you put a mass along an animal's back, the top of that mass wouldn't curve inwards, because there wouldn't be anything to press down upon it in that manner.

For your leg constructions, overall your use of the sausage method is coming along very nicely. I did notice some places where the feet you were drawing - especially on constructions like this bear simply didn't receive as much attention as they could have. There's no good reason to say that the feet shouldn't be constructed as thoroughly as everything else, and there's certainly no way to excuse leaving this otherwise excellent hybrid's feet as plain boxes. These are areas where you're simply making the choice not to explore them further. There are often these kinds of situations where we'll find that it feels like we just end up doing something without being conscious of it. These are of course situations where we still choose to take that course of action - and taking responsibility of it is the first step to better control our intentions and what we ultimately end up doing.

The last thing I want to touch upon is just how you've approached the areas of furry detail. Here I think you relied a lot on somewhat repetitive patterns, zigzagging back and forth to create quick tufts of fur or hair. The thing about fur is that it needs to be designed. The more corners we cut, the quicker we try to do it, the more poorly it actually conveys the impression we're after. It is infinitely better to spend all your time on a single tuft of fur, and just to have that one intentionally designed element on your animal, then to put quick, sloppy jaggies all over the construction.

I've got some notes on how to approach fur here in the lesson, but really the key is to avoid going into auto-pilot. Humans are exceptionally good at picking up patterns, and we can tell when an artist has just allowed their subconscious to take control. Instead, shape each tuft intentionally, taking care and thinking about how every stroke is drawn. This takes a lot of time, and it's okay if it means you end up drawing less fur - frankly, you don't need that much to convey the impression that an animal is furry. Always aim for less-is-more.

Aside from those points, I think you've done a great job. Your observational skills here certainly are continuing to improve with everything else, and while that still has a good deal more growing to do (I felt your bears in particular suffered from perhaps not spending as much time observing your reference), your skills are coming along quite nicely overall. I'll go ahead and mark this lesson as complete.