This is a rough and tumble guide, meant to demonstrate the concept, not beauty. The beauty you make from this guide is up to you. You may want to play around with various pillars to see what works best.
To get things off the ground, let's get things off the ground using pillars. You probably already know about pillars, but just know you can put pillars on top of one another, then build on top of it.





Pretty ugly, right? All those pillars and no space?





Well don't you fret. You can delete all those pillars under it (but not the pillars directly under your building. So it will look like this




Cool! A floaty building!





Now your possibilities are endless. Use it to extend your school above the ground and leave space for ample parking. Or do the same trick on a roof, and build pools, baseball diamonds, helipads or whatever underneath and have your school extend above it. Or just have it stand alone and add stairs or elevators to it.








Just remember, this is a rough guide. My example is ugly. However your imagination and experimentation will help make a more beautiful school.