1. Couplets

2. Couplet
Couplets are any two lines working as a unit, whether they comprise a single stanza or are part of a larger stanza. Most couplets rhyme (aa), but they do not have to.
In Couplet poems, lines 1 and 2 rhyme, and lines 3 and 4 rhyme (not necessarily with lines 1 and 2). There are usually 4-6 lines to a verse.
Both lines are similar in length according to the number of syllables

3. Into my empty head there come a cotton beach, a dock wherefrom
Couplet
Into my empty head there come a cotton beach, a dock wherefrom

4. Couplet
Decorator Hermit Crab There was a little hermit crab Who thought his tank was rather drab At first he didn't know what to do Then decorated with pink and blue. Now he is no longer crabby With his new home, he's rather happy!

5. Couplet
Twas the night before Christmas, when all through the house Not a creature was stirring, not even a mouse;
The stockings were hung by the chimney with care In hopes that St. Nicholas soon would be there.