You and probably the school district should have an international tax specialist review the arrangement to determine:

1. the extent to which the payment may be subject to US tax and withholding.  The question is whether all or any portion of the payment is effective connected income (ECI) or FDAP;
2. whether tax treaty provision(s) may apply;
3. the payor's responsibility to withhold, remit, and report, which will affect your cash flow; and
4. your liability for tax filing and payment, if any; and
5. assist/guide you with the application of an Individual Taxpayer Identification Number (ITIN) or Employer Identification Number (EIN).

Instead of a W-9, which is only applicable to only to US residents, what you should provide is a W-8BEN (or W-8BEN-E if the contract is with an entity).  An ITIN would be required if the income is reportable to you as an individual or EIN for a foreign entity.  The forms are mandatory for the certification of US tax status, so, neither you nor the school district can get away with not complying.