Do you know what is a codex and what is a scroll and the difference?
You can get better explanation from your LDS Bible Dictionary on pg. 647, but briefly scrolls were read using rolls that went side by side from one end to the other. It would be necessary for you to unwind one end until you found what you were looking for. A codex is usually a bundle of papers (or papyri or plates) bound at one end, similar to how the Book of Mormon was bound at one end by rings, thus the plates were actually a codex.
Now you can get up in class and say that you beleive in the ancient codex compiled by Mormon.
From this verse we know that metal was also used for record keeping in the Middle East:
1 Nephi 4:16
And I also knew that the law was engraven upon the plates of
brass.