the highschool "lot" only exists in the expansion world and cannot be added/moved to other worlds (the building itself can but the lot type is exclusive to the expansions world).
Its been commented on by many reviewers as a lost opportunity and makes little sense because its not like San Myshuno, which is clearly a large city wouldn't have its own school zoning but no...you can't place a school lot in it. No matter where your teenagers live - they have to catch the school bus and go to the new neighborhood.
One theory was because the school has a football field and bleachers behind it...except you can't sit on the bleachers or use the field for any events like grad or you know...sports lol. So that theory doesn't make sense...
The other theory is because the highschool needs to be close to the grad building or in the same neighborhood...but than just make that a requirement, that you must place both in the same neighborhood.
Honestly this is something that needs to change and can be changed in a future patch and for me is the biggest issue I have with the pack (and lack use real use of the sports field...)