A simple sentence is one complete thought with someone or something doing an action. A simple sentence is one independent clause.
Sometimes, an independent clause has a compound subject. A compound subject is two people or two things doing the same action.
Look at this simple sentence with a compound subject. Notice that there are two animals doing the same action.
The dog and the cat ran across the street.
The subject of this simple sentence is The dog and the cat. This is a compound subject.
However, the dog and the cat are doing one action – they ran across the street.
This is a simple sentence with a compound subject.
Here are more examples of a simple sentence with a compound subject:
Bob and Mary rode their bikes.
Mom and Dad took a walk.
Mr. Smith and Ms. Johnson are directing the school play.
In each of these sentences, two people are doing one thing.
Look at these simple sentences with a compound subject:
The trees and bushes are bending in the wind.
Boxes and crates are piled in the corner.
Parents and their children are lined up at the ticket window.
The compound subjects in these sentences are things instead of people, but each sentence has only one action.
A simple sentence sometimes has a compound subject.
▶It’s your turn. Find the compound subject in this simple sentence: Jim and Sue bought a new car. Did you find the two people who are doing one thing? Good for you!