Experienced Missionary (EM): As you remember from last week, Joseph Smith translated the Book of Mormon from ancient metal plates, using the Urim and Thummim.
New Missionary (NM): Uh, actually, Joseph didn't really translate anything.
EM: What do you mean?
NM: He didn't even use the plates. They were under a cloth the entire time he was dictating.
EM: Elder/Sister, that's not what we...
NM: Don't you read the Ensign? Or Book of Mormon Central? Or watch the latest videos? Seriously, Joseph just read words that appeared on a stone he put in a hat.
Friends (looking at EM): Last week you told us Joseph Smith translated the plates.
EM: He did. I mean, that's what I thought.
NM: That's what people used to think. But the Church historians have figured out that Joseph never translated anything, after all.
EM: What about the Urim and Thummim?
NM: When Joseph and Oliver Cowdery said he used the Urim and Thummim that came with the plates in Moroni's stone box, they actually meant Joseph used a seer stone he found in a well years earlier.
EM: Then where did the English translation come from?
NM: Someone from the 15th or 16th century produced it. It's sort of a "cultural" translation of what was on the plates. At least, that's our best guess right now.
Friends: Why don't you come back when you get your story straight? In the meantime, we'll just consult the Internet.