Grammar 
Reduced Relative Clauses
Definition: To put it simply, reduced relative clauses take the relative pronoun (that/which/who/where) out, AND the verb following the noun always ends in ~ing. In the example sentence below, the words "that are" were taken out to form this grammar point. Do I agree that this grammar point should be taught this early in the acquisition of a second language? No.
Example: "The people answering the telephones are operators."
More example sentences & in-depth definition