Explication of a line of poetry from "Dulce et Decorum Est":

QUOTATION TO EXPLICATE: "As under a green sea, I saw him drowning."

EXPLICATION:  "Dulce et Decorum Est."  Wilfred Owen.  The speaker describes a soldier's death by poison gas.  In a simile  comparing the gas to a "green sea" the word "green" suggests an eerie light coming through the thick gas, and the word "sea" connotes an almost liquid thickness as well as the volume and spread of the deadly agent.  Furthermore, the assonance in "green sea" along with the contextual implications of the color green suggest an evil, sickly event, and the word "under" linked with "sea" suggests the how deeply engulfed the speaker is, and how desperate the situation is.  There is also a sense of being smothered and overwhelmed in "under."  The speaker's words, powerful in their simple, direct, monosyllables, "I saw him," emphasize the immediate personal horror of the scene, and "drowning" stresses the terrible struggle to breathe, as well as the desperate flailing and "floundering" of the dying man.  War is horrible, not glorious.
 

An explication is a complete analysis of all important words in a passage.  It shows how meaning is built throughout the passage.  Note the parts of the answer.  The first two elements of the explication are title and author.  Next comes a brief summary of the situation, with out too much plot summary.  Then comes the meat of the answer, a detailed analysis of the language and its effect.  An explication does not just tell what a work means, but how it means.  Finally the answer ends with a brief summary of the whole meaning of the quotation.

Tips

1) Don't use a full sentence to give title and author.  Use full sentences only in your explanation.
2) Always aim at explaining how the text develops meaning, both through individual words in context, and by words and phrases working together in the larger context of the work as a whole.
3) Focus on specific words, one at a time, and explain connotations.  In many quotations it will not be necesarry to discuss every word, so underline words to be discussed, choosing the most meaningful ones.
4) Note irony, similes, metaphors, imagery, alliteration and other poetic devices.  Mark the text to show connections, how they work, etc.
5) Avoid vague, general statements.
6) Avoid wordiness and repetition.
7) Avoid simple plot summary.
8) In some cases you may be able to link the overall meaning of the quotation to  similar works studied together.

P.S. You'll probably need to do some of this kind of analysis in your interpretive papers, and reading notes that contain this sort of analysis will earn a considerable amount of credit.

P.P.S.  Because students sometimes don't realize that they are summarizing plot, I'll give simple plot summary below.  This is what you need to avoid in order to do well on this assignment:

In the poem the author describes what it is like to be in a gas attack.  He says it is like being under a green sea, where you can’t breathe.  It sounds terrible.