If you have a computer, you probably have a printer that scans photographs. Whether you took the photos or someone else did, the point of scanning is to get the picture. That’s what scansion (aka scanning a poem) does too. It shows your eye what your poetic ear can hear. When you read a poem aloud, you can hear yourself give more emphasis to some syllables than others. Usually your voice will skip over “business words” such as prepositions (to, of, on) and articles (a, an, the), but you just naturally place more stress on the strong verbs and nouns. Those nouns provide pictures for your poems, and then the active verbs move the pictures along. Let’s take, for example, the last half of the above sentence and use capital letters to note the accents or stressed syllables: and ACTive VERBS MOVE the PICtures aLONG Listening for those accents or beats is what you do when you scan. Then breaking the line into groups of two to three syllable creates the poetic meter known as feet. To define: An iamb is two syllables with the emphasis on the second: and ACT/ tive VERBS/ aLONG/. The opposite of an iamb is the trochee, which also has two syllables but with the emphasis on the first: MOVE the/ PICtures/ So put it all together to scan the sentence, and you’ll see three iambs and two trochees. Since that adds up to five feet and the Latin for “five” is “penta,” the line is pentameter. If a line of pentameter has more trochees than anything else, you’d have trochaic pentameter. In this line, however, the iambs outnumber the trochees, so presto! You have the famous iambic pentameter. Even though that sentence was not particularly poetic, you get the picture. Scansion shows you the emphasis or beat that you hear as you read a poem aloud. So your eyes can now see what your ears hear. What difference does that make? Maybe none! If, however, your poem loses its rhythm or seems to have no musicality as you read aloud, then scan the poem. See where it loses the beat. For instance, you might find that you have three or more unstressed syllables together. Those feet have names, too, but the point is, they show you that you need to tighten the beat. How? Change words around, or find new words that have the emphasis where you want.
This article also appears over at Poetry Editor and Poetry