Your teacher is asking for a personal reaction with this question. The poem was written during World War I and reflects the realities of war. The title reflects a segment of the final two lines of the poem, written in Latin: It is sweet and fitting to die for one's country.
The author, Wilfred Owen, wrote the poem about his experiences of fighting in the trenches in World War I. Through the imagery in the poem, Owen challenges the mantra that appears in the final two lines. Indeed, he argues, it is not a sweet thing to die for one's country. The poem describes death on the battlefield as horrific and painful, robbing young men of their lives while their fellow soldiers look on helplessly.
It would be difficult to read this poem and not react to the unspeakable horrors of war. Following a sense of honor and duty, many men and women have joined wars (voluntarily and involuntarily) to defend countries, kings, and leaders throughout history. While these soldiers are often revered for their wartime efforts, this poem is a reminder that gruesome endings befall many who enter wars. The visual imagery of the young man who dies while "blood / Come[s] gargling from [his] froth-corrupted lungs" often makes readers cringe—yet this type of death is a typical reality for those who fight the world's battles. The auditory imagery of the man dying while "guttering, choking, drowning" provides a sensory assault that is shocking, particularly to those who have never fought in wars and may be removed from the reality many soldiers face.
In answering what the question makes you think about, you might want to consider relatives and friends you have known who have fought in wars. Often these people avoid speaking about what they have heard and seen on battlefields across the world, and this poem provides some insight about why those topics are so difficult to mention. You might also consider touching on particularly realistic dramas that portray the gruesome realities of war, such as Saving Private Ryan, released in 1998. Or the poem might make you consider with new reverence the more than one million Americans who serve in the nation's military, possibly facing the same horrors as are represented in the poem, in an effort to keep the nation safe.