Both of these images accomplish exactly what was asked from you for this assignment. Your first image provides the illusion of the movement of water by using a slower shutter speed, while your second photograph provides the illusion of depth by using a shallow depth of field.
From not only a technical standpoint, but also a compositional standpoint both of these images are very strong. That being said, there are a few areas I would like to direct your attention.
My main concern is with your first photograph (the waterfall). If you enlarge the photograph you’ll notice that it has a slightly washed out look to it. This is likely because you let in more light than you normally would have due to the longer exposure time. Notice the area around the rocks are even “blown out” (i.e. overexposed) and lack detail and texture. They are just white blotches. This means there is missing digital information that can’t be recovered in post production. No information exists in those areas. It’s not as noticeable until you enlarge the image, but it’s important to take into consideration nevertheless.
It’s caused by limitations of digital technology. Digital cameras have a hard time handling latitude (also known as dynamic range). In fact, we’ve written an entire blog post on the subject here:
http://photographyicon.com/blog/2008/11/26/digital-cameras-latitude-dynamic-range/
Please take the time to review the article above. It will help you greatly for future assignments.
The second photograph however is very well done. You’ve simplified the color palette of the shot to a only 2 colors; gradients of greens and browns. Not only that, but you’ve limited your objects to just 1 primary element (the squirrel) and 1 secondary element (your background) which makes the photograph incredibly easy to look at. The composition and object placement is also very well though out. Great work!