Don't knock it until you've tried it. I feel it is only fair that I assess each student individually. Your opinions may differ, but that's what I believe. How do you assess oral English? Many years ago I sat down and wrote an assessment and accompanying rubric and spreadsheet. It sits on my laptop. I also have about 30 students per class, like the OP, and a 90 minute period. I do not give a mid-term, so the school allows me to use the last two weeks of the school year to give my finals. I divide the class in two by student ID numbers and the first half of the class (@15) comes the first week of finals and the second half the second week. So the assessments are done during regular class time. The assessment is in three parts. The first minute is a listening test. I read 10 pairs of similar sounding sentences and the S simply tells if they are the SAME or DIFFERENT. (E.g. "The old man smelled." "The old man smiled."-DIFFERENT) This takes one minute and counts for 20 points (20% of their final grade). The second part is pronunciation. I have them read ten sentences with a few pronunciation issues embedded (e.g. "usually," "think," etc.). I just listen and starting at 40, I subtract one point for each error. I divide (or rather the computer divided) the final result in 2 so the pronunciation score accounts for another 20%. I then have a large group of TEM-4, CET-6, TOEFL-type Topics (eg. "If you were the mayor of this city, what would be the first thing you would do.", etc.) I choose one and read it and give the students 20 seconds to prepare. They speak for about 2 minutes and I'll ask them one or two questions on topic for another minute. All the while, I have my spreadsheet in front of me and am typing in scores for Comprehension, Vocabulary, Grammar, Fluency, and Creativity for a total of 50 points (10 apiece). Finally I give them up to 10 points for Class participation 9Which I have previously determined and input into the spreadsheet. Wen they finish, their final score is already computed (though I don't tell them). And though I'll take a quick look through all the scores, I rarely have to make many adjustments. I can literally print out the spreadsheet and hand it in immediately after the class, if necessary. I arrange two rooms. The tsudents sit in one. I usually bring a DVD for them to watch while they are waiting. The sound from the DVD (which I can hear from the next room) covers the sound from myself and the student I am examining. It takes about a minute in between students (which is when I recheck their score) so 6 minutes/per student = 90 minutes. And I'm done as soon as the last student leaves. No student in the same class gets the same question. While they could possibly try to record the first part (the minimal pairs sentences) and let their classmates listen, I've never caught anyone, but being aware of it, I watch closely and I also mix up the sentences (eg. "The old man smiled." The old man smiled." SAME

I would hate to have to go back and do it any other way. I'd hate to have to sit in a room while students give prepared speeches or sit around listening to pairs or groups of students struggle through some topic AND try to get a listening score out of that tp boot. So don't knock it until you've tried it. It's much, much easier if you take a little time to prepare for it the first time (i.e. make the spreadsheet, collect the questions). After that it's a breeze.

P.S. This is my first post. I sometimes read this site, but the negativity really turns me off. So go ahead and flame me as seems to be wont here, but sometimes the glass IS half full in teaching in China.