IN what way is the teacher treating the students unequally? On what basis? There are a myriad of potentially applicable laws but one would be scattershot in answering without much more detail.
Both the 14th Amendment and the 1964 Civil Rights act protect agianst race, religion and nationality discrimination, likewise gender (though it is not subject to the same level of scrutiny) Title IX also provides protection in terms of gender equality. The ADA and the 1973 Rehabilityation Act provide protections for the disabled as does the Individuals with Disabilited in Education Act (IDEA).
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