At one elementary school they had Cosmic Osmo. The next had the early Mac CD with both Fate of Atlantis (Talkie) and Secret of Monkey Island. I'd love to say that I played MI more at the time, but we were competing to beat FoA (and trading saves back and forth on floppies), which of course we never could in the time we had in computer lab. FoA had Indiana Jones and voice acting, it was the obvious choice for elementary schoolers... MI is obviously my preference of the two today, though.
My first real Sierra adventure was The Castle of Dr. Brain (yes, I declare that it was an adventure game, it was an AGI game after all). At one point I was so proud having beaten both The Castle and The Island of Dr. Brain. Early in my computing history my parents were buying a lot of Sierra, Broderbund, et al edutainment titles (they were running a couple of computer learning centers for kids, well ahead of their time) and it wasn't until just about High School that I really started getting into the larger world of adventure games outside of Humongous, but I was just in time to buy many of the late greats before the decline...