Maybe. Contracts can be oral, written or "implied in fact," meaning by the parties' conduct. You seem to be describing an implied in fact situation, based on the change in payroll.
The issue of the school being obligated to honor your original contract, whether signed or not, depends on what its language says, and no lawyer on Avvo or otherwise can guess what that is without reviewing it. If the school had the right to transfer you to a different position, then the action of changing payroll is less important than their subsequent exercise of their right to transfer you.
PLEASE READ THIS BEFORE YOU COMMENT, EMAIL ME OR PHONE ME. I'm only licensed in CA. This answer doesn't make me your lawyer, and neither do follow-up comments and/or emails and/or phone calls, and you shouldn't expect me to respond to your further questions if you haven't hired me. We need an actual agreement confirmed in writing before any attorney-client relationship is formed. This answer doesn't constitute legal advice, and shouldn't be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue.
Contracts with a Texas public school district have to be written and duly signed to be enforceable under Texas law. Texas law will not enforce an oral contract with a school district, as it is a governmental entity with sovereign immunity.
If the contract as signed by the district calls for 202 days, you should be paid for 202 days, particularly if you worked 202 days. If you only worked 187 days, the answer may be different. I recommend that you check with your local teacher's organization to see if other teachers have been similarly shorted, and have the teacher's organization go to bat for you. Keep in mind that Texas is an at will employment state, which means that the district can lay you off at the end of your contract for any reason or no reason at all, just not an illegal reason. (Retaliation under the right circumstances may be an illegal reason.)
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