A repeated line does not have to mean exactly the same thing each time it appears. In a pantoum, its new neighbours can change the weight of an ordinary statement: a sentence that first describes a room may later sound like a memory, a warning or a reply.
The Academy of American Poets’ guide describes a sequence of four-line stanzas in which the second and fourth lines return as the first and third lines of the next stanza. The form has roots in Malay poetry and has been adapted in different traditions. Endings and rhyme practices can vary.
Read the returning line in its new company
Here is an original two-stanza practice fragment, not a quotation from a published poem:
The kitchen clock has lost a hand.
The cups are waiting by the sink.
I leave the window open wide.
There is more time than I had thought.The cups are waiting by the sink.
Your train has passed the final stop.
There is more time than I had thought.
The room grows quiet in the rain.
In the first stanza, waiting cups might suggest an unfinished household task. Beside the train in the second stanza, they can suggest an absent visitor. The words have not changed, but the possible relationship between them has.
To study a complete pantoum, mark each returning line with the same colour. Read straight through once without stopping, then follow only one line through its appearances. Ask what the new surrounding lines add, remove or make uncertain.
Finally, inspect the ending. Does it return to the opening and make that opening feel different? Does the poet alter a word or punctuation mark? A small change can matter precisely because the pattern has trained you to expect repetition. The form is worth reading as a series of changing relationships, rather than as a puzzle whose only reward is identifying the repeated lines.