At the age of 9 my parents were told by my arts and crafts teacher that it would be better for me and the world (!) that I would never ever hold a needle again. I heard that and I really believed I couldn't do anything with a needle.
At the age of 33 I got the greatest teacher in the world. Within one lesson I was quilting 20 stitches on an inch, upside counted. I do handapplique and my goal is to have a quilt juried in in Houston or Paducah.
Now who was not capable, the teacher or me?
Teaching is not something you can do easily. Especially children and beginners should be encouraged to try, to experiment. Your SIL should not walk, but run out of class. If these teachers are not professionals, why would she want to learn from them?
Have fun quilting!
Emphasize fun.
Anymart