I suspect a challenge here is that there's simply not that great a need for schools, and that office buildings tend to be far more clustered than school needs are.

If higher education, schools also typically have a range of classroom / lecture room sizes which office building are poorly suited to match. Seminar-to-classroom size (5--30 students), perhaps, but not mid-to-large lecture halls (100--500 or more students), without some major redesign.

Though theatre conversions might work. I'm thinking of a lecture hall with Imax A/V capabilities....

That's one potential alternative use, I'm sure, but probably not the best.

As cool as this sounds schools need to be located in the neighborhoods they serve. Some central business districts have few residents as they are purely zoned for office buildings and parking garages. Taxpayers are also allergic to paying for premium real estate. (Sometimes to their own detriment. e.g. Building a new school on the outskirts of town saves money on land acquisition but results in slower and costlier school bus routes and parents use more time dropping off their kids).

>Some central business districts have few residents as they are purely zoned for office buildings and parking garages.

I think this is exactly the problem many folks are proposing we solve, by doing things like changing out some of that unused office space dor schools and housing.

It's basic market economics. Use the space for things we need, things that are in demand and space for which is scarce, not for things that are in surplus and have a flooded market.

Use the space for things we need; but also eliminate needless segregation of services; Live + Work + Play.

Schools (and housing) not located near business districts results in roads, with traffic. And for schools versus businesses two ends of the same commute (train or car)