After meeting with the school's superintendent, Chris Kell, Morrison was told that her contract would not be renewed for the following year.
"Your decision to incorporate the worksheet associated with the novel 'Dear Martin,' due to the content and subject matter," read a letter from the superintendent.
Kell told the News-Leader that the school board is unlikely to change its decision on the matter.
"I would think at this point it is a done deal. It was a board vote," Kell said. "They are the ones that do the hiring, the non-renewals. It was their vote."
Kell also noted that Morrison's firing was the first time that accusations of critical race theory had been pinned on a teacher in the district.
"We have the best interests of our students, our community, our staff," he said. "That's why we are here. We are trying to provide that school district that everybody can be proud of. In a situation like this, it comes down to a school board vote at this point. I don't feel like we teach critical race theory in our district."
Morrison, for her part, said she was "deeply saddened" by the development, noting that "if this is how they terminate teachers – without asking questions, without speaking to the teacher – then no one is secure."
"And if they are opposed to broadening, to examining, their viewpoints," she added, "they are not doing students any good."