My DS is 5 and his friend's mother has just died.
I had wondered if the school might tell the class, but they didn't, though they have made the parents aware. Some of the other parents think it's best not to tell them (class would be 5/6 years old) but I'm not sure.
When this little boy comes back to school he's going to have lost his mother and that's going to have affected him. The reason other parents think it's best not to tell them is that they may ask gory questions about burial and skeletons, or talk about death to an extreme with this little boy.
If anyone has any advice it'd be appriciated.