Changing the AF Point
The reason most of your are taking this class is you have only used your camera's in auto mode so far. This is going to be something you guys are going to LOVE about being in manual and will change your life once you get it down.
In manual mode your camera allows you to change your focus point. This is not the AF/MF on your lens (keep that on AF), but this is something in your manual menu that you can change as you take each photo. The grid looks like the one I placed on these three photos (when you look through your camera's viewfinder. As I line up my shot, I move the dial around this grid until the square is red that I want my focus to be on. (this will help with your aperture assignment as well if you are able to change where your camera is focusing)
Left photo: focus on Caleb's eyes
Middle photo: focus on his crackers
Right photo: I kept the focus in the same spot but as he moved his fire engine around I focused on that. (notice I got more blur compared to the crackers because the truck was closer to me than the crackers were)
Look in your manuals for something similar to "changing the AF point" and follow those instructions. In the 3rd photo of the DSLR...this is where it should be located on most of your cameras. I push this button and then I have a dial towards the front of my camera that I'm able to slide around to the correct point to focus on. (The 2nd photo shows where it is on your camera screen but when you are looking through your viewfinder you can't see it). You will see the squares like I placed on the photos of Caleb. This takes a ton of practice...just getting the coordination of it, but to me it is something I do now without even thinking about it now. Just make sure you do it for each photo you take and you'll be a pro in no time. In your auto mode, your camera will generally focus on what object is closest to you. So I wouldn't be able to achieve these effects the way I wanted if I was in auto.