Exams

The exam period at Lyon 3 occurs between the end of classes until the beginning of the new semester. The summer exams occur from the end of classes until the end of June.

Sweaty palms, rapid drop in body temperature, dry mouth, fluttering stomach, nervous coughs in poorly-ventilated rooms, intellectual black-outs... The previous are commonly my experience during exam time and this does not bode well for my success in the French system.

Taking Your Exam as an Exchange Student
The time and place of your exam is usually posted up the day before or the morning of your exam on the corresponding boards of your faculty. Be sure to consult these lists because there is assigned seating. The exam period at Lyon 3 occurs between the end of classes until the beginning of the new semester. The summer exams occur from the end of classes until the end of June.

As an exchange student in the law faculty, if it is not already written on your exam, you will be given stickers by Annie Simon - the secretary of the law faculty - that you can stick on the front of your exam (I'm assuming that outside of law, you go see the secretariat of whichever faculty is responsible for the majority of your courses).
Even though it's readily apparent that you are an exchange student, sometimes, there are foreign students who are studying in France, not on exchange, who also have bad grammar but are marked at the same level as French students. You, however, are a foreign student on exchange and thus not marked as harshly for your grammar and spelling mistakes. It's better to get the stickers.

Equal = Anonymous
In France, there is an equality rule in place that is particularly strict when it comes to exams. You are not to write your name on any other part of the exam except in the designated space at your top right hand corner, after which you fold and glue shut. Your name is revealed only after the grades are finalised.

I'm not sure how this affects exchange students but in France, since the education system is an organ of the Republic (like the health system, like the army, like the police....), if a student is caught cheating or plagiarising, s/he is automatically barred from taking any sort of exam (this includes driving exams, entrance exams for other schools) for five years.

Le carnet de notes
You are asked to bring with you to each exam a booklet (carnet de note) for your professor or the invigilator to fill out, which you then hand in to your faculty before leaving. This is where all of your grades will be recorded and then mailed to you or your school.

On a final note, I've been told that while exams are a supremely stressful time for French students (I've been told that France has one the highest failure rates in the Union), as an exchange student, you need not be as worried because they understand that things are more difficult for you. As long as beneath the bad grammar and spelling mistakes you reveal a fundamental understanding of the course material, you should be fine.
And when that doesn't happen... It was nice living in France for a while, wasn't it?