It’s pretty stupid because it doesn’t follow convention – but that’s actually exactly how I learned it in school, so it’s not like there isn’t precedent.

Here is (roughly) what I learned in elementary school (in Bavaria): http://i.imgur.com/LbQ7l.png

I think the J dropping below the baseline isn’t particularly uncommon or unique. (I know quite a few famous typefaces in which the J drops below the baseline: Baskerville Old Face, Lucida Grande, Palatino, Rockwell, Optima, …) However, the I looking like a J certainly is, at least in print.