A simple sentence contains a subject and a verb, and it expresses a complete thought.
1.Many students study in the mornings.
(Contains one subject and a verb)
2.Julia and Amelia play chess every afternoon.
(Contains a compound subject and a verb)
3. Ruby oes to the library and studies every day.
(Contains a subject and a compound verb)
NOTE: A simple sentence may contain a compound subject,( as in sentence 2)and may contain a compound verb.(as in sentence 3)
Simple sentences, therefore, contain a subject and verb and express a complete thought, but they can also contain compound subjects or verbs.
A compound sentence contains two independent clauses joined by a coordinating conjunction. The coordinating are as follows: for, and, nor, but, or, yet, so. (Helpful hint: The first letter of each of the coordinators spells FANBOYS.)
1.She tried to speak French, and my friend tried to speak English.
2.It was raining, so Manasa stayed at home.
3.Manasa stayed at home, for it was raining.
4.The teacher was explaining, but the students were not listening.
The above sentences are compound sentences. Each sentence contains two independent clauses, and they are joined by a coordinating conjunction with a comma preceding it.