Hello, good job on finishing lesson 3! Here's my critique:

Organic arrows

Some arrows ended up looking nice, some not so much. As you're probably aware, there are lots of places where the lines don't connect to the arrow. If this is repeated throughout the page, arrows start to lose their solidity and you lose the illusion of 3D form. This also hold true for overshooting the shadows, so do your best to avoid it. Remember to take your time and invest as much care into individual lines as you would when doing a real painting. Of course mistakes happen, however there's a noticable difference in mistakes that happen when you're trying your best and mistakes caused by rushing. I have this problem as well, and the wise words of someone who critiqued go: "Ironically, rushing through the exercise doesn't make you improve faster".

The visual clarity is also lost on this area, the viewer can't tell what is in front of what. You can add subtle line weight to indicate the part of the arrow that's in front. You also added too much shading, to the point it started to blend with the shading from the upper fold. Remember to use as little lines as possbile to visually communicate what you're trying to achieve, in this case it's shading. Applying these 2 changes like this helps the viewer understand how this arrow sits in 3D space.

Speaking of 3D space, most arrows only have a slight variation in size over their whole "body". Go out of your comfort zone, try starting your arrows very tiny and going up to huge sizes like 1/4 of the page. I find that overlapping arrows over each other adds a lot of visual confusion to yourself (remember in this exercise you need to convince yourself that you're looking at a 3D space), so rather take a new sheet of paper where you can draw freely. That's just my suggestion, if you find that you can handle it, you can overlap arrows.

Lastly, to reinforce the 3D space feeling, the distance from each arrow fold should be shorter the further away from us it is. The best example is this arrow. Instead of doing that, try drawing your arrows more like this. To recap, here's a visual explanation.

Leaves exercise

This one is mostly fine. Sometimes you're zigzagging your lines and sometimes you're cutting inside the leaves rather than building from them. When you repeat this exercise in later lessons, make sure to read the "common mistakes" under leaves section again. I also see some rough lines that may be the result of rushing, but I'm not sure. I cannot stress enough how putting the same amount of care and attention to every line is important, so I'm mentioning it here again. In my studies, I noticed I was subconsciously rushing my lines when the exercises got tedious, so I limited myself to constructing 2 plants per day.

Branches exercise

I can see that you're trying your best here, other than a few small branches. Even though some ellipses look rough, all of them are drawn confidently and that's the most important thing. Good job!

Plant drawings

Your construction is good as far as I can tell, the plants look 3D. I'd have to see the references to detect smaller mistakes. I'm noticing a bad habit when it comes to your textures, and that is the fact that most of your textures are composed of dots with almost uniform distance between them. I do see that you're making an attempt to go from dense to sparse with them, but you could push it even further. It's important to consider that a texture can be represented with a very little amount of lines and dots actually. Let's say you're drawing a dotted sphere, you would only need this much texture to convey the material, the human mind fills in the rest automatically. Also call back to the texture exercise from lesson 2, that black border we had to merge with the shadow shapes is the same one that happens on real objects. You have to completely conceal the shadow line border (idk how to call it, I mean this) with gradual dense to sparse texture, just like you did in lesson 2.

Watch out for spacing out lines by the same distance! This doesn't happen in nature, it's always random. Always have this on your mind, alternate between small, medium and large distances.

In conclusion

Even though I critiqued a lot, I'd say you understood the purpose of each exercise. Before moving you on to the next lesson, I'll ask of you to do two pages of the organic arrows exercise and one page of table of ellipses from lesson 1 (I placed the links in the revision section). I'm asking for 2 pages of organic arrows because I think you can improve here quickly, just take your time with each line and consider everything I wrote about this in my critique. I'm asking for a table of ellipses page because I think your ellipse accuracy will benefit from drawing more of them. Good luck!