The term 'GRAMMAR TEACHER'S CONCERN' can be summarized as the USAGE of language, which is a five-letter word. Grammar teachers are concerned with the proper use of language, including grammar, syntax, and punctuation. They strive to ensure that students understand the rules of language and are able to apply them correctly in their writing. USAGE is an important part of language, and grammar teachers must be knowledgeable about the correct USAGE of words and phrases in order to effectively teach their students.