eli the teacher

I had my class again today. That is, the english class in which I help out on tuesdays. Today I got there and handed the teacher the tests I'd graded for her (almost uniformly in the top 15% with one outlier who got like a 55% and I'm sure there was a ton of copying because I preserved the order of the tests from when she handed them to me and the wrong answers followed unmistakable patterns between tests that shifted as I graded down the stack of exams). She told me, thanks, this is great, I'll be right back I have to go get a CD can you do these exercises with the class, and then left. Woops.
I was lost for about 3 seconds but I took control of myself and the class - Jumping around, trying to get everybody involved at once. It's hard! The problem is that the classroom is big, it has no echo but neither does sound carry at all, and there are a lot of kids. I'm thinking more than 40. Discipline is kind of a forgotten dream in general there, and especially when I have no disciplinary power whatsoever. But they respected me somewhat, I think for being new and because I had a lot of energy. We read exercises and filled in blanks. The first time I tried to get a kid to speak up and tell us the answer he did so, and then I said, "Ok, did everybody hear that?" It was met with a resounding "No!"
But we worked along, I helped kids with different things, I switched up strategies, and things went smoothly. I even think most of the kids were having fun. Honestly, the teacher didn't come back for a full 15 minutes (leaving me alone is expressly against English Opens Doors rules, but I had the time of my life).
The rest of the class was less exciting, although she did leave me alone again for like 5 minutes later on. For next class, we're going to do an activity together where they'll work in small groups trying to fill in sentences the fastest, and then the group that gets the sentence filled will get a chocolate or something. Is that too "elementary school" for 16 year olds? I know I always want candy, even now...