Question Summary:
Can a Muslim attend the funeral of a non-muslim?

Question Detail:

A Christian teacher at my childrens High School, who they were really fond of, has passed away. They would like to attend his funeral but I don't think they're allowed to. I've been told that they aren't even supposed to make dua for him. Can someone learned, please shed more light on this for me, Shukran
 
If you could, please comment on the information in this link as many use this as guidance. 
 
http://spa.qibla.com/issue_view.asp?HD=1&ID=3287&CATE=168

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
We deeply apologise for the much belated response.
Children consciously and more often unconsciously adopt the tendency of some of their teachers. The possibility of the Christian teacher’s tendency rubbing on to our children cannot be ruled out.  The influence of the Christian teacher in the enquired case is a clear example of that. It is therefore important for parents to exercise caution in the choice of their children’s school especially to guard their Deeni values and beliefs. 

And Allah Ta’āla Knows Best
Immad Bin Arshad
Student Darul Iftaa
USA
Checked and Approved by,
Mufti Ebrahim Desai.