CathInfo.com

Unreasonable. They may be part of a property firm seeking to buy the building. School districts offload closed venues all of the time. It cost them a seven-figure sum to build, and when districts no longer have the need, they sell them. Happens a lot.

Not unreasonable.  Recall the Israeli “art students” and “movers” at 9/11.  Who knows if some fαℓѕє fℓαg operation isn’t in the works?  Except if it’s really Israelis, they’ll get cover from our government agencies.  You wrote this fact off as not suspicious but to me it’s the MOST suspicious ... that they took a picture of you.  They were obviously concerned about being watched.  

If they were doing nothing wrong, no harm done.  I would consider anyone staking out a school suspicious ... whether they’re planning to abduct children or perpetrate some fαℓѕє fℓαg attack. Israelis are known to be involved with cнιℓd тrαffιcking (cf. Les Wexner, Epstein, Maxwell, etc.) as well as fαℓѕє fℓαg terror (cf. 9/11 and USS Liberty), being the “by way of deception” crowd.  If they have some legitimate non-criminal reason for their activity, then it could quickly be cleared up.  Otherwise, it’s possible that you helped to deter some criminal act.  Of course they’ll just find another target.

And, yes, it’s very possible to spot Israelis based on various physical characteristics.