what is a simple sentence?

[sallyhoudongmei]

"The students I teach have made better grades in the past few weeks."
Is it a simple sentence or complex one? As far as I know there is an attributive clause "I teach" in the sentence, thus I think it is not a simple sentence because there are two sets of "subject and predicate" structure. While there is a grammar book think this sentence is still simple sentence because "I teach" is used to modify one of the words or phrases in the sentence, not be a part or component of the sentence (if it is, it should be complex: e.g. What he said is not true), that's the book's opinion.
I am confused as I think all kinds of clauses are just "clause", if there is any clause in a sentence, the sentence can not be called as simple sentence. I know most of the attributive clause (the definite one)is used to modify a word or phrase, according to the book, is that to say, most of the sentence including an attributive clause is a simple one?
Thank you !!

[Pedroski]

"The students I teach have made better grades in the past few weeks."

This sentence contains a zero relative clause: '(that) I teach'

It could be written:

"The students that I teach have made better grades in the past few weeks."

It contains a main clause and a dependent clause, and is therefore complex.

[sarat_106]

Originally Posted by sallyhoudongmei

"The students (who/m)I teach have made better grades in the past few weeks."
Is it a simple sentence or complex one? As far as I know there is an attributive clause "I teach" in the sentence, thus I think it is not a simple sentence because there are two sets of "subject and predicate" structure. While there is a grammar book think this sentence is still simple sentence because "I teach" is used to modify one of the words or phrases in the sentence, not be a part or component of the sentence (if it is, it should be complex: e.g. What he said is not true), that's the book's opinion.
I am confused as I think all kinds of clauses are just "clause", if there is any clause in a sentence, the sentence can not be called as simple sentence. I know most of the attributive clause (the definite one)is used to modify a word or phrase, according to the book, is that to say, most of the sentence including an attributive clause is a simple one?
Thank you !!

A simple sentence, also called an independent clause, contains a subject and a verb, and it expresses a complete thought. The subject can be a compound subjects or a compound verbs. If there are more than one clause in a sentence, it can be a compound or a complex sentence. In the example sentence there are distinctly two clauses.
MC. The students have made better grades in the past few weeks.
SC. I teach.
The subordinate clause does not convay a complete thought. So it is a dependent clause apparently joined to the main clause by a relative pronoun who(m) not shown here. So it is obviously a complex sentence