There's only one presentation I remember, and it wasn't my own. One of my classmates (I'll call him T.J.) had brought in his guitar. Plucking the strings in turn, he described how each string vibrated at a different frequency, and how the diameter of the strings and the tautness with which they were cranked affected the pitch of each note. He strummed a few chords in illustration of the harmonic quality of notes played concurrently, then launched into a brief few chords of a popular song to drive the point home. And maybe show off, just a little.
The song was R.E.M.'s "Losing My Religion." Those of us in that classroom in 1992 all knew it (I'm pretty sure anyone alive anywhere in 1992 would), and so when T.J. hit the first verse, a few of the more outgoing in class started singing. Not to be outdone, T.J. joined in, too, and before the end of the first verse, the entire class was in on it. And didn't stop.
And what might have been silly, or nerdy, or sad, or ridiculous, somehow wasn't any of those things. Not a single person held back. Not a single face snickered. No eyes were rolled, no hair twitched with mock exasperation. We just looked around at each other and sang our hearts out. With every verse, the class grew more exact in their vocal performance, until what was pouring out of that classroom wasn't so much just a collection of voices as it was a group impersonation of Michael Stipe. Complete with breaks and bends, and breaths in the right places, we sang the hell out of that song, all the way to the end. And as T.J. strummed the last few notes quietly, there wasn't a single one of us who wanted to breathe and break the spell.
I took a lot of classes in high school and was fortunate in having more than my share of truly dedicated and talented teachers. I experienced many moments that will stay with me. But this one is one of the most vivid. I don't know what T.J.'s doing now, or where he lives. I don't remember much else about that semester in Physics II. But for that one moment, I had a perfect high school experience, and it will stay in my mind that way, always.
I bet he got an A.