Hey, who's the teacher here? Ha ha ha. Whether you're using conventional CDs or burned CD-Rs like we produce, the data is stored just under the label NOT on the "down" side. The down side is really nothing more than clear plastic to give the CD strength and shape. The data is "burned" on the back side of the CD-R label. If you don't believe me, see this article.

The problem we had was that the new CD-Rs I purchased didn't stand up to the cold very well. The CD got cold and the label flaked off. I'll post some pictures of some of the CDs that people sent back to me. It's not pretty. When the label flakes off, that's all she wrote. The data is on the backside of the white label (coating). The rest of the CD is just clear plastic. Don't believe me? Crack one open and see for yourself.

The reason why CDs don't work if you scratch the bottom side is because the laser has to shoot up through it. If the path of the laser is obstructed, the data can't be read. If you look at any of those home "CD fixer" kits, what they basically do is grind away and polish the bottom of the CD to remove any scratches, but the DATA is still stored right under the label.