A sentence diagram is a picture of a sentence that puts every word where its job belongs. The kind used in American schools was published by Alonzo Reed and Brainerd Kellogg in Higher Lessons in English (1877). It starts with the two parts every sentence has: the simple subject and the verb.
- Draw a horizontal baseline.
- Write the simple subject on the left part.
- Draw a short upright line that crosses the baseline. It splits the subject from the verb.
- Write the verb, with all its helping verbs, on the right part.
Key idea
Place each word by its job, not by its place in the sentence. Subject left, verb (with its helping verbs) right, on one baseline split by a line that crosses it.
Why it works
A diagram shows what reading aloud can hide: which word is the subject, which is the verb, and how every other word hangs from them. In a question or a command the words are out of the usual order, but the diagram is the same, because the jobs are the same (Hard-to-Find Subjects).
Worked example: A question
Diagram “Did Mia call?”
- Turn it around: “Mia did call.”
- Subject: Mia. Verb: did call.
- Write Mia left of the dividing line and did call right of it. (Some books keep the capital: Did call.)
Answer: Mia | did call
Worked example: A command
Diagram “Listen.”
- A command’s subject is you, understood.
- Write it in parentheses: (you). The verb is Listen.
Answer: (you) | Listen
Common mistake
Copying the words in sentence order instead of placing each by its job, and putting helping verbs off the baseline. The whole verb phrase (were laughing, has been waiting) sits together right of the dividing line.
Textbooks draw a few details differently (the angle of a slant, where a conjunction sits). These lessons use the usual form, as in Reed and Kellogg’s Higher Lessons in English and most American grammars; if your book differs a little, both are fine.