I think that you should not dwell on the subject too much. I have an student with Autism and I only allowed him to do ONE journal topic on the attacks. On September 12th, we were given the day off. When we came back on the 13th, I had him to write about how he felt about the attack, from what he understood and what he did on his day off.
Anyway, I think that like other professionals have suggested, we should try NOT to let this CONSUME us. It probably is hard, but I think that if the students are going to want to discuss this, let them discuss it with their parents. You know you tap into issues of religion, morality, the reason why, etc. To keep yourself in a "safe zone", go on back to business as usual.
I say, move on to writing essays, subject/verb agreement, etc.
You should really move on if you all have to administer state-wide standardized tests.
That's my opinion.
