<p>Although I am in an adminsitrative position now, I taught for more than 15 years. I always did my own grading, and I cannot understand how anyone can claim to be a good teacher or even interested in improving his/her teaching and not grade most of the students’ work. How do you know whether they understand the material? How do you know where the problems are? How do you know when your tests/assignments are unclear or faulty in some way? I taught at a liberal arts college where classes ranged in size from 15-30 max. with an average of about 50-60 total students per semester. </p>
<p>Obviously, if a professor is teaching a huge lecture class with hundreds of students, it would not be possible to grade all those papers oneself. H occasionally teaches such large classes but he always takes time to look over some of the work in order to prepare guidelines/troubleshoot for the TAs who will be doing the grading. </p>
<p>Unfortunately, it is a trend throughout education. Science/math books often publish answer keys for some or all of the problems (mostly so the students can check their work without the prof having to grade it). Many textbook series provide objective pre-written tests to relieve the prof of the task of writing tests and to shorten the time needed to grade.</p>