INDEPENDENT CLAUSES can stand alone as sentences.
My class is wild.
DEPENDENT CLAUSES/PHRASES have a structure that indicates their dependence upon another (i.e. independent) clause:
PARTICIPIAL PHRASES function as adjectives that describe nouns/pronouns and begin with -ing or -ed.
My class, screaming and fighting as soon as the bell rings, is wild.
APPOSITIVES are noun phrases that restate or identify adjacent nouns/pronouns.
My class, a group of high-energy students, is wild.
RELATIVE CLAUSES begin with who/whose or which/where and give more information about adjacent nouns/pronouns.
My class, whose enthusiasm for distraction is palpable, is wild.
ABSOLUTE PHRASES contain both a subject and a verb (in the form of a participle) of its own. Absolutes are almost complete sentences. As a test, you can make any absolute a sentence by adding was or were.
My class, pencils flying, is wild.