It is pattern-making in a 3-dimensional way (not by drafting). You place a piece of cheap muslin on the dress form mannequine, and then do whatever you can to shape it into a dress (or a shirt, or a pant ) that you design. You do folding, cutting, pinning, measuring.......WHATEVER. For example, if you need a dart on your skirt, you have to gather the extra fabric and make adjustment and smooth out until you got the fit that you desire, then you pin the dart and make marks. After you remove the muslin from the dress form, you draw lines according to the pins and marks to guide your sewing. Our teacher said in order to draft a good pattern on paper, you need to have clear concept of draping first. You could also duplicate a favorite piece of garment that you have with ease (without having to rip it apart) if you have enough draping knowledge.
I am not good at this becuase I have a very poor sense of spatial relationship. You really need to be able to shift your mind between 2-D and 3-D quickly in order to do nice draping (and pattern-making I guess). You want to ask me what the hell is spatial relationship? Well, remember the kind of questions in an IQ test that ask you what an odd-shaped box will look like from a different angle? That's it. I got zero point at that part of my IQ test, which is good, becuz I feel I am entitled to be slow and dumb at our draping class. It's stress-free.
To watch that piece of muslin slowly change into a piece of clothing right on the manneqine.......it's totally magic.
The collar & the sleeve.
When you sew the bodice and skirt together, the darts and side seams have to line up.