Diagramming sentences is no longer taught in most schools. Like cursive writing, it has been supplanted in the curriculum by computer-related skills and critical thinking skills which for most children are more important.
Yet diagramming offers children a fun way to learn grammar and parts of speech which themselves are not focused on as much anymore, and which has led to poorer writing and difficulties on parts of the SAT (my opinion).
What is diagramming? Diagramming is a visual way of showing the grammar in a sentence, everything from subjects, predicates and clauses to prepositions, subordinate conjunctions and gerunds. If a child can draw a straight line, he can diagram a sentence. And if he can diagram a sentence, he can “see” the grammar.
For example, take the uncomplicated sentence of “The baby noisily slurped mashed bananas from a spoon.” It can be diagrammed by first drawing a horizontal line where the main parts of the sentence are written (similar to the trunk of the human body). All the nonessential information is written on slanting lines under the main line (much like appendages of the body).
On the line to the left always goes the subject of the sentence (in this case the word “baby”). A vertical line cuts through the line to show the end of the subject and the beginning of the predicate.
The first word of the predicate in a diagram is always the verb (in this case the word “slurped”).
If there is a direct object (in this case, “bananas,” it is written to the right of the verb and separated from the verb by a half line which does not cut through the horizontal line.
Prepositional phrases are put beneath the word they describe, with a forward slanting line for the preposition (in this case, “from”) and a small horizontal line for its object (in this case, “spoon”).
Adjectives and adverbs are shown beneath the words they describe on forward slanting lines.
The grammar of much more complicated sentences can be shown through diagramming. Doing this helps children see that a particular “sentence” has no verb, or that the reason a particular prepositional phrase sounds funny is that it needs to go next to the noun it describes. When students learn that subjects or objects can themselves be clauses, a diagram can make this clear faster than a long-winded explanation from a teacher.
Many handbooks on English grammar contain chapters on diagramming, showing examples of various types of sentences. If your child is struggling to learn grammar, using those handbooks might make grammar visually intelligible the way a table, chart or Venn diagram makes data more easily intelligible than a paragraph of explanation.
But don’t expect your child to come home from school with diagramming homework, as I once did. Most of the young teachers today don’t know any more about diagramming than does your child.