Simultaneous communication as used in classrooms is here analyzed to determine how well it represents English grammar. Samples of the communication used in teaching were collected from two hearing teachers as they conducted regular classes at a large residential school for deaf children. Comparisons were made between teachers’ spoken and signed utterance with respect to grammatical construction, including declarative sentences, questions, relative clauses, pronoun use, and verb tense in English, and to such specifics as facial expression, head and body tilt, eye gaze, and use of space in American Sign Language (ASL). Results showed that signed utterances were predominantly ungrammatical with respect both to rules of English and to rules of ASL. The need to institute stricter requirements so that teachers of the deaf become better equipped to use simultaneous communication as well as other forms of communication is made salient by this study. Related issues requiring further research are also considered.