Both of these photographs are wonderful and accomplish exactly what was asked from you for this assignment.
In your first photograph you create the illusion of depth by using a slightly shallow depth of field. This helps isolate your foreground from your background while still allowing your background to provide context.
In your second image you’ve decided to freeze movement by using a fast shutter speed.
Both of your images are technically strong. You have sharp focus, clear composition, good framing and you’ve used your manual controls wisely. However, there is 1 issue I would like to point out. Your exposure is a little too high.
You have “burnt out” (also called “blown out”) areas in both photographs, but most noticeably in your water photograph. Notice in both the front of the cup and the top of the frame there are large sections of pure white. This area has been completely overexposed and all of the digital information in these areas have been lost. This is a common problem within the realm of digital photography because digital cameras have a difficult time handling “latitude” or “dynamic range”.
Your first image of the cake minimized the burnt out areas (only small parts in the top right corner), but I want you to be aware about it in both photographs.
We’ve written an entire article about the subject here:
http://photographyicon.com/blog/2008/11/26/digital-cameras-latitude-dynamic-range/
Please read this article as it will help you avoid this problem again in the future.
Other than that; great work!