Quilting is my creative hobby/outlet. So when frustrated, I give myself permission to burn it. As far back as I can remember, I set my own standards. But when I taught my daughter, I had to listen very closely to what she was really saying, not just the words. I love the book, "Bending the Will, Without Breaking the Spirit." Some things are just not that important. I have to choose the eternally important things, on which to take a stand.
So, how important is a 1/4" seam at this point in time? Only you can answer that.
You've gotten some good ideas for teaching it. When I teach a newbee, they start on a piece of prelined paper and just try to stay on the lines, no thread. Then I help them do a little math; 1/8 inch x 80 seams = 10 inches. Usually show them a quilt with 80 seams, like a log cabin. Beyond that, if it'll stay together and not pull apart, it's probably OK.