No, at least I can’t. Appearance doesn’t help at all. I am glad I grade papers, not people, because if I guessed by how a student looks, I would be better off rolling dice. Then at least I would know that it had no relation to reality.
There are clues as to who will be a good student from the beginning of the semester. The student who comes to me and offers excuses as to why he will be late to class, miss class, or otherwise not fulfill the requirements of the course is probably not a good student. However, the student who is concerned enough to come in the first few days expressing doubts about his ability to do well, and requests information as to what can be done to improve his chances, is usually an A or B student.
The student who gives me a sob story as to why he won’t do well, won’t do well. The student with a handicapped child or a dying sister, which were both verified by external sources, will probably flunk. I once told a student who took three weeks off in the middle of a semester to care for her sick grandmother on another continent, “I’m not saying you didn’t make the right decision, but there are still consequences for your decision.” In other words, no matter how good your excuse, you will still get the grade you earned.
The student who comes prepared is usually a better student, but even that is sometimes misleading. I want them to bring their books to class, but the student who doesn’t bring a book may simply take a bus to campus and takes four different classes in a day. Books are heavy, and the way I run a class, they can be shared. But the student who doesn’t have paper, pencils or a calculator is probably not a good student.
I make no attempt to add up the clues, because I identify good students by their homework, quizzes, and tests.