Pretty sure they're doing nothing, probably faking it so the others can hear them and think teacher is treating them as his wives.
Which is stupid cause I think the students wouldn't mind not faking it :p
It's nice to see a manga with actual development between characters.
There are so many stalling for like 50 chapters without any progress (Amano Megumi wa Suki Darake!, I'm looking at you right now...)
I'm always scared with this kind of manga that the story will suddenly go tragic with deaths and shit. So far it's rather emotional and funny, but it always seems to be on the edge. I'm afraid things will turn to shit with Ikariishi pretty soon.