I am sorry for the later response. I was away from my computer. I appreciate the responses to my questions as they give me direction here.
First of all, they cannot legally hold your last check. They have no legal right to withhold money from you for hours you have worked. You can sue them based on that alone if you so choose.
Unfortunately, the termination (though unethical) is likely legal. It sounds like you were an at will employee. This means that you can be terminated for any reason, or no reason at all, believe it or not. That said, the employer cannot terminate you if the reason is discriminatory in nature. Moreover, you cannot be terminated based on your age, race, gender or disability. Furthermore, if other teachers have been involved in similar situations and have not been terminated, then you may have a case for discrimination if that teacher or those teachers fall into a different category than you.
If you feel as though you have been discriminated against you can file a complaint with the EEOC office in your area. They will investigate and if they find merit, will allow you to sue in federal court for damages. You have to file this complaint within 180 days of the date of your termination.
If you find out that they have breached their own policy in terminating you, then you can sue in state court for wrongful termination as well. You need a copy of the policy and procedure manual to make sure that is the case.
So, they cannot hold your last check and you should send them a certified letter with a return receipt which points that out. Give them three business days from the postmark to make it available or you will sue for it and damages as well.
They likely can terminate you in this manner, but cannot if it differentiates from treatment of other teachers in similar circumstances in the past that are not in the same classification as you (race, gender, etc.).
Let me know if you have any other questions or comments.
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Best wishes going forward!