Downfall of Western Roman Empire?

Your teacher probably expects you to mention:

1) barbarian incursions notably the Vandal conquest of North Africa, which deprived the western Empire of vitally needed grain and revenue.

2) Civil wars like the one between Boniface and Aetius, which further weakened the empire.

3) Lack of adequate support from the wealthy, who had large estates and resisted taxation.

In my opinion, though, christianity was the root cause of the fall of the western empire. Obsessed with their new faith, the christian citizens of the west would no longer identify strongly with the Empire and fight for it. The empire had to hire barbarians but they proved untrustworthy and gradually seized the empire for themselves.

The Roman Empire had always recovered from foreign invasion, plague and civil war--until christianity sapped its strength in the fifth century.

Better the Vandals you did not know than the tax collectors you did.

That is what led to the fall of Rome.

As for "discussing and analyzing," I think your TEACHER wants to know what YOU think.