<p>“When your son was churning out practice essays, how could he tell he was good, not just because he’d finish in 25 min?
did someone help to grade?”</p>
<p>&1&2, there was a scoring rubric (chart) in one of the old SAT-II Writing Tests, and is probably also in the shiny new SAT-I books I hope. It defined marking standards for a 1, 2…6 score. I know as a teacher that we use those rubrics to grade, so I assumed the SAT-readers do similarly. They are all the same idea, but ratcheted up for each score point. For example, under “sentence variety” it might say for l, “no variety” and for 2 “one example with a varied sentence…” and up to “5” might say: "shows mastery of sentence variety in many places of the essay, but a “6” could be “shows master of sentence variety throughout the essay.” You get the idea.
Anyway, I’m just a humble elementary school teacher, but after my S wrote the first one, I read it and “graded” it the way I imagined they might, and discussed it with him against the rubric. I was slightly tough on him 
but not blistering.
The second time, we each graded it separately. I wanted him to start thinking about the rubric as he wrote. Our scores were nearly identical!
(That’s interesting, too, b/c I think I recall that if the actual SAT test scorers (2 per essay) come up with scores different by more than 2 points, they automatically hand it over to another reader.
Honestly, on that last point, I could be confusing this with another test. It’s late as I write this.)</p>