Good question. I have noticed on my press foots and marking on the plate of the machine...1/4 is not what it shows to be! I literally had to measure from needle to ...... wherever and choose a foot that had that measurement. THe quilt 1/4" foot isn't 1/4" but my all purpose foot has a perfect side to needle of 1/4" so I just have the fabric follow the edge of the pressure foot. I'd say on the other problem...as long as they are very near, why wouldn't they be okay? As long as you are persistant in that measurement. Maybe the teacher is trying to teach them structure or persistance. I have found sometimes in cutting thesquare out, that I have to cut them a slight 1/8" bigger than I want them to be because when I sew the exact measruements together...they are all off and crooked but that scant 1/8" literally saves the day!