You use sentences every day, but have you ever thought about what exactly a sentence is?
A sentence is a group of words that expresses a complete thought.
In order to express a complete thought, every sentence must have two parts.
1. Subject (someone or something)
2. Predicate (what the someone or something is being or doing)
That's it! A sentence is just someone or something being or doing something. Simple, huh?
When we diagram sentences, you can always see those two basic parts. The stuff on the left side of the vertical line is the subject and the stuff on the right side of the line is the predicate.
Sentence diagramming is a visual way to show how the words in a sentence are related. Sentence diagrams will help you understand sentence construction.
Making sentence diagrams feels more like completing a word game than it feels like working on grammar.
You saw in the picture above how the basic diagram of a sentence works. The subject and verb go on a horizontal line and a vertical line divides them.
This is true of the very simplest type of sentence and the most complex type of sentence.
Here is a diagram of a very short sentence.
Here is a diagram of a very long sentence. This is the Preamble to the United States Constitution.
It's just one sentence, and it's pretty complicated, but notice that in the upper left corner, you can see the vertical line dividing the subject and the predicate.
Don't worry too much about those things now. Just focus on the fact that even really complicated sentences are divided between the subject and the predicate.
Some groups of words don't have what it takes to be a complete sentence.
If a group of words is missing one of those two key elements we talked about (subject + predicate), it is a sentence fragment. A sentence fragment is a group of words that does not express a complete thought.
When you read a sentence fragment, you are left wondering whom or what the sentence is about or what happened in the sentence.
You can change a sentence fragment into a complete sentence by adding the missing information.