Students need opportunities to check in with each other around their learning, ask questions, guide each other and reflect together. And this is even more crucial with a large class. If a tight classroom space won't allow for quick triads or quad grouping, use "elbow partners" -- two students in close proximity. Do this often. As we know, with large class sizes, quiet students tend to get even less airtime. With less one-on-one time with small groups and individual students, teachers need to keep that large number of kids talking and being listened to. You can do a "turn and talk" even for just 27 seconds. Much can be discovered, wondered about, and solidified in that half a minute.