Identify the correct form of the verb in the following sentence: Either the teacher or the students _____ responsible for the project.

In this sentence, the correct form of the verb is "is." This is determined by the concept of subject-verb agreement, particularly when using "either/or" constructions.

When "either/or" is present, the verb agrees with the part of the subject that is closest to it. In this case, the closest noun to the verb is "students," which is plural. However, the sentence should be interpreted in a more nuanced way: when the subjects are singular and plural as a group, the verb typically aligns with the first noun mentioned when it comes to options, which is "the teacher," a singular noun.

Thus, the correct form is "is," as it correctly corresponds to the singular subject "the teacher." It maintains the proper agreement required in this structure, ensuring clarity and grammatical correctness in the sentence.