The 607 keeps being suggested so I think I will get that book and research it. Though, I need to keep it as simple. And when it comes to numbers, dates and math, I myself tend to get lost.
I haven't tested this method but how do think this would go over:
Ask one or Jewish friends/acquaintences when Jerusalem was destroyed (both times). If they don't know right away, they should find the 'Jewish Account' pretty quickly - like with just a phone call to their rabbi. (Heck, you could even call a rabbi yourself. But 'asking acquaintences' sets up your alibi that you were witnessing to friends and they corrected your false date.)
Then visit the library and ask a librarian to help you find the answer to the same question. Have the librarian make a copy for you.
Present that simple discrepancy (JWs have different dates than Jewish and Secular history) to your mom and let HER do the research and explain it to you.
Let her do the leg work. She may find more info than just what you've prepared for her...
While she's researching and calculating dates, you could be doing the same with Alleymom's and AlanF's and others notes.
This was good news. I look forward to reading about the next session.
-Aude.