I think all the comments about him being bald and such are just ripples from the main problem, which is the ridiculing Mags endured. I know when I took the SAT essay section, I had to think for a while as to what I would write. I'm pretty sure they actually recommend you spend about 5 minutes brainstorming (planning out your introduction, two or three body paragraphs, and a conclusion) before you do any writing at all. It sounds like you were pressured into writing something that you hadn't even thought of yet, which is inappropriate, and not very helpful. After that, it sounds like the teacher was way out of line with his lecture, and I'm sure Mags said some things he otherwise wouldn't have said.
My only SAT preparation came in late 10th grade, but mostly 11th, when I actually took it. Anything done earlier than that, I see as being a bit silly, but if you're going to do it anyways, it shouldn't be anything stressful.
That's just my two cents.