Of oral exams and how to mark them

One of the most difficult issues of this brand-new subject is how to evaluate our students’ oral productive skill. When taking oral exams, we have to face two problems:
a) Oral exams take a long time (and our groups are quite large)
b) How do I mark my students? What´s the criteria?

a) Well, that’s a fact. If we have a group of 20 students, let’s give them about 5 minutes each student. That makes 100 minutes plus the necessary time between every student’s turn: 3 lessons. However, what if we make our students examine in groups of 2 or 3 people? In fact, that’s what I have just done in the first term. I asked my students to make groups and hand in a project containing oral texts recorded in any type of files they liked. All of them (the group is made of 17 students) decided to make a video. We watched all the videos in class, which took us two lessons (100 minutes).
b) Talking about the marking of oral exams, I firstly thought of using a single mark to evaluate every student, but I realized that it wasn’t fair. Finally, I decided to mark four different aspects:
1. Pronunciation
2. Fluency
3. Intelligibility
4. The project
Points 1-3 evaluate their speech and point 4 does the video. So students get 4 different marks (the final mark comes from finding the average) and that helps them to know which parts they have done well and which areas need more practicing.

Well, I haven’t written all this for my students, but for any teacher who may read it and wishes to comment on it. I would really appreciate if you post a message talking about your experience on doing and marking oral exams. Thank you very much!