The 5th class - group discussion in Multi-media Classroom (11/8)

The 5th class was the time I reserved for students to have group discussion because I intended to reduce their workload since they just finished a big project in Unit6. I borrowed the Multi-media Classroom because it's a better place for 42 students to discuss in groups. However, I realized some "little chaotic" situations from my teaching there. First, it took a long time for students to arrive there, and attention catching in that classroom was totally a challenge to me. I found I had to "yell" even when using the microphone to get students' attention. I felt embarrassed and honestly, I don't like to yell in class. :( Second, just like Alice's suggestion, students got distracted more easily in Multi-media Classroom, therefore, the visual aids were more indispensable. If I had projected the answers of grammar exercise on the screen or asked students to share their answers in the front, the situation might be better. Third, I should have required students to discuss IN ENGLISH in the beginning. Fourth, I should have reconfirmed if students understood what they had to do with the handouts or forms. If several students repeat the same questions, then announcing publicly again may be the best solution. But I found it's difficult to examine if students discuss diligently or not. What should I do if I realize students in certain group didn't do their job? Should I correct them immediately, or wait for their performance on presentation day? Because in my opinion, some students who are typically viewed as "naughty, absent-minded" may have inspiring creativity! So what's the better method for me to deal with the order maintaining in discussion class? Mmm...I have to think more about it...