There are at least two. One on each side of the school. Sure, for the first one you have to pretty much flatten the larger part of a hill to be able to build anything, and on the second one there's a playing field of some sort (you can just paint over that, though) but both these spaces have room for even a 50x50 lot.
They're not perfect, but usable.
You're right, BUT....(lol), the playing field is actually part of the school complex although not part of it's lot. Some of it, the bleachers I believe, are part of the school, so it would look really dumb to put a building there unless you removed the bleachers. Which, of course, is totally possible.
I did put a building on the other spot but it was pretty tricky getting things lined up and looking ok. Check out my post on the Showboat thread to see what I mean.
I'm thinking there may be more sports type stuff coming along, like some of the things we already have, or rather to use them, so covering up the playing field is on hold for me.