Actually there's an interesting point re learning hidden in the above:
If you shoot Manual, and your shots are incorrectly exposed when reviewing on the PC, you have no way of knowing what the light was like, so your baseline isn't set. If you're thinking exposure compensation in a semi auto mode, you can experiment with that and see what effect +1 stop or -1 stop looks like.
I don't see much point in taking one shot as you can't tell much from that but if you take more than one shot you can see and learn something. For example take one shot with the cursor smack in the middle of the exposure scale and then take more shots changing the aperture, shutter or ISO as you go and so causing the cursor to move to the right / left hand side in turn. Also, changing the value of one thing and then changing the value of the others to keep the cursor in the same position may help to understand the exposure triangle.
Yes, sure, but Phil is still right about Manual not necessarily being the best way to do this.
Imagine you take three shots with different exposures and look at them afterwards to see which was best. If you shoot in Manual, the Exif data says:
* f/8, 1/100th, Manual mode
* f/8, 1/200th, Manual mode
* f/8, 1/400th, Manual mode
Whereas if you shoot in Aperture Priority mode, you get exactly the same three photos, but now the Exif data says:
* f/8, 1/100th, AP mode, EC +1 stop
* f/8, 1/200th, AP mode, no EC
* f/8, 1/400th, AP mode, EC -1 stop
Surely the second of these is a more helpful learning tool.