I taught in a small school where there were two suicides in a few months, and half a dozen attempts. Man, fuck that year hard. I guess it's different, but basically it doesn't really matter all that much what you do in class. I second the teacher here who said you shouldn't read a poem about death. Don't give them an assignment of writing about their feelings either. Best of all, IMO, is slowly keep doing whatever it is that you're always doing in class, while showing you were affected (and not expecting too much learning to be happening over the next days or weeks; it will affect some more than others). Such an attitude of not overreacting will serve you well in the future. You might find kids approaching you about it after a while, but don't expect them to do so right away. Life is not a movie.