Closed Form Poetry
The Bedford Online Glossary defines closed form, or "fixed form" poetry as follows:

[Closed or fixed form poems are those] that may be categorized by the pattern of its lines, meter, rhythm, or stanzas. A sonnet is a fixed form of poetry because by definition it must have fourteen lines. Other fixed forms include limerick, sestina, and villanelle. However, poems written in a fixed form may not always fit into categories precisely, because writers sometimes vary traditional forms to create innovative effects.

What distinguishes closed form poems is that they develop regular patterns with regard to lines, meter, rhythm and stanza. When we discuss a poem's structure, we're observing its pattern of lines and stanzas.

THE LINE: A line of poetry is characterized by its length and meter, which are created by the number of syllables and where their stresses fall.

THE STANZA: A stanza is a group of lines, visually distinguished from other groups of lines by white space. Fixed form poetry usually maintains regular stanza pattern, and there are a lot to choose from:

The Couplet: two line stanza, rhyming aa
The Tercet: three line stanza, rhyming varies
The Quatrain: four line stanza, various rhyming patterns

Quatrains:
Ballad quatrain: rhymes abcb
Heroic quatrain: rhymes abab
Rhyme Enclosure: rhymes abba
Triple quatrain: rhymes aaba
Double couplet quatrain: rhymes aabb

The Quintain: five line stanza
The Sextain (sestet): six line stanza

Poems with CLOSED FORM STRUCTURES are those with predetermined patterns of lines and stanzas.

These are some of the better known structures with their definitions based on information from the Bedford Online Glossary:

The Epic A long narrative poem, told in a formal, elevated style, that focuses on a serious subject and chronicles heroic deeds and events important to a culture or nation. The oldest piece of literature is the Epic of Gilgamesh. Homer's Iliad and Odyssey are epics. In English literature, John Milton's Paradise Lost is an epic.

The Ode A relatively lengthy lyric poem that often expresses lofty emotions in a dignified style. Odes are characterized by a serious topic, such as truth, art, freedom, justice, or the meaning of life; their tone tends to be formal. There is no prescribed pattern that defines an ode; some odes repeat the same pattern in each stanza, while others introduce a new pattern in each stanza. Some of the oldest odes are probably those written by the Greek poet, Pindar (Victory Odes). A couple of my favorites are written by two 19th century English poets, both romanticists -- John Keats' "Ode to A Nightingale" and Percy Bysshe Shelley's "Ode to the West Wind" (p. 723).

The Ballad Traditionally, a ballad is a song, transmitted orally from generation to generation, that tells a story and that eventually is written down. As such, ballads usually cannot be traced to a particular author or group of authors. Typically, ballads are dramatic, condensed, and impersonal narratives, such as "Bonny Barbara Allan" or "House Carpenter." A literary ballad is a narrative poem that is written in deliberate imitation of the language, form, and spirit of the traditional ballad, such as "Ballad of Birmingham" by Dudley Randall or "Ballad of the Landlord" by Langston Hughes (p. 828).

The Sonnet A fixed form of lyric poetry that consists of fourteen lines, usually written in iambic pentameter. There are two basic types of sonnets, the Italian and the English. The Italian sonnet, also known as the Petrarchan sonnet, is divided into an octave, which typically rhymes abbaabba, and a sestet, which may have varying rhyme schemes. Common rhyme patterns in the sestet are cdecde, cdcdcd, and cdccdc. Very often the octave presents a situation, attitude, or problem that the sestet comments upon or resolves, as in John Keats's "On First Looking into Chapman's Homer." The English sonnet, also known as the Shakespearean sonnet, is organized into three quatrains and a couplet, which typically rhyme abab cdcd efef gg. This rhyme scheme is more suited to English poetry because English has fewer rhyming words than Italian. English sonnets, because of their four-part organization, also have more flexibility with respect to where thematic breaks can occur. The several sonnets we'll study are "My Mistresses Eyes Are Nothing Like the Sun" (p. 712), "Ozymandias" (p. 903); "The World is Too Much with Us" (p. 710), and "Unholy Sonnet" (p. 714).

Villanelle A type of fixed form poetry consisting of nineteen lines of any length divided into six stanzas: five tercets and a concluding quatrain. The first and third lines of the initial tercet rhyme; these rhymes are repeated in each subsequent tercet (aba) and in the final two lines of the quatrain (abaa). Line 1 appears in its entirety as lines 6, 12, and 18, while line 3 reappears as lines 9, 15, and 19. Dylan Thomas's "Do not go gentle into that good night" is a villanelle.

Open Form Poetry
The Bedford Online Glossary defines open form, or "free verse" poetry as follows:

Sometimes called "free verse," open form poetry does not conform to established patterns of meter, rhyme, and stanza. Such poetry derives its rhythmic qualities from the repetition of words, phrases, or grammatical structures, the arrangement of words on the printed page, or by some other means. The poet E. E. Cummings wrote open form poetry; his poems do not have measurable meters, but they do have rhythm.

What distinguishes open form poems is that they do not develop regular patterns with regard to lines, meter, rhythm and stanza. Their structure is more "organic" instead of being predetermined, following its own inner logic according to the emotion or thought expressed.

A few open form poems to consider are Two E. E. Cummings poems to study are "l(a" (p. 514) and "When I Heard the Learned Astronomer" (p. 904). Can you identify whether the other poems on the exam study guide are open or closed forms, and why?