When I offer classes to learn my machine for future renting time we always start with muslin top & bottom because it's inexpensive and you can see what you are doing. Generally we would use a couple yards ( 44"X72") for practice and contrasting ( dark colored thread)
after learning the machine, threading, winding bobbins, cleaning, oiling, setting up stitch size, tension, etc. we would work on the muslin quilt top. First just some free motion to get the feel of it, learn to write on it, then drawing some designs to follow. Try a pantograph, put on the ruler base & try some ruler work.
My class is 4 hours. If after the practice quilt the student is comfortable and has time & brought a small pieced quilt we load that up and let them quilt it. A Queen would be too large for a practice quilt. For years if I wasn't working on a real quilt I had a muslin practice quilt loaded. My family & friends often stopped in & (played) practiced and I practiced on that quilt. We did all kinds of things with the finished ones, grandkids loved using fabric markers & coloring the stitched quilts. We cut them up, finished edges and donated them to the animal shelter, we made things with them.