Disclaimer: my own high school had a phenomenal English department. Do many teachers simply plop a score at the top?
This is the problem, they can't. They can do the 80% to make it understandable but the last 20% is always the hard bit.
It'll happen one day, but it might be up there with the singularity for when it's viable. Fully understanding a paper to grade might equal AI intelligence on par with humans.
Not to say perhaps a quick hack, like a 80% grader that the teachers quickly look over to check and correct might be a game changer.
See the comment by aaron695 who made a very good point about feedback.
I wonder though if there is some easy fruit at the bottom of the tree i.e. elementary school - where I gather grading is probably a lower burden and easier to formalise - although I am probably again greatly understating the problem.
Now, I believe that the education system of the majority of the world is fundamentally broken - and I am cheering on the likes of coursera, khan academy and the like to get to fixing it.
But in the mean time...can we take the first of these...grading. At the risk of trying to find a technical solution to everything this sounds like it should have a nice technological solution to it...
I can see some of the issues in English and the like where answers may not be 0 or 1 but if google can instantly translate English to Swahili...someone should be able to find a way to grade English assignments of high school student efficiently.
Or is this a money issue? The technology exists or could exist but there is no funding, so instead we are wasting hundreds/thousands of teacher hours a week while they repeat the same manual chore over and over again?
I would be interested in hearing some teachers comment on this.
Reminds me of this: http://www.ted.com/talks/geoffrey_canada_our_failing_schools...