Although you will get a ridiculous answer or none at all, I think you should ask a couple of questions at the end. That way you are letting them know that you require some response, this is important particularly if you are doing it so that your dad can see your efforts.
You could ask them something like -
If I am to remain a Jehovah's Witness would I be required to believe that the flood was global and occurred around 2300 BCE? Would I also be required to teach this to others and not express my doubts amongst my fellow Brothers and Sisters?
Also, are you able to provide evidence of where my understanding is incorrect?