Six short lines, and almost nothing in them is explained. A laugh and a smile belong to someone, and the speaker wants both repeated. We never learn who "you" is, or whether that person is in the room or only in memory. The poem doesn't say, and that silence is part of its power. What remains is a pure wish: *again*.
The central idea is that delight in another person is made of small, fleeting gestures, and that wanting them repeated is a kind of devotion. The speaker offers no adjectives. The laugh is not "bright" or "warm," and the smile is not "dazzling." Both are simply named and claimed. Praise would have limited them, and the poem trusts the bare nouns to carry everything the speaker feels.
The construction is a tight mirror. Each three-line stanza follows the same pattern: a thing ("The laugh"), the thing made personal ("Your laugh"), and a command ("Sing it again"). Moving from "The" to "Your" feels like a camera drawing closer. The laugh begins as one that anyone might have, then becomes this particular person's. Repeating the structure in the second stanza turns the poem into a ritual, almost a chant, and it is also a small joke on itself, since a poem about asking for repetition repeats itself.
There is no rhyme in the conventional sense, but the poem has a strong sound pattern. Both stanzas end on the same word, "again," so the whole poem is bound by one identical rhyme that returns just as the speaker asks for the gesture to return. The stress falls on the second syllable ("sing it a-*gain*"), so each stanza ends with a lift, like a voice rising to plead. The rest of the rhythm is clipped. "The laugh." and "Your laugh." are tiny two-beat lines, and the full stops after every fragment make them land like separate bursts. That suits the subject, since laughter itself comes in bursts.
The two verbs are the most carefully chosen words in the poem. Laughter is told to "sing," which turns a spontaneous sound into music and makes the speaker an audience asking for an encore. The smile is told to "flash," and the sense shifts from ear to eye. A flash is sudden and bright, and it is gone almost as soon as it appears. That brevity may explain the demand. A smile that flashes has to be requested again, because it cannot be held. So the stanzas split the beloved into the two ways we perceive a person's happiness, by hearing it and by seeing it, and the poem asks for both.
The tone is hard to pin down, which keeps it interesting. The imperatives "Sing" and "Flash" could be tender, like a child begging for a favourite song. They could also be greedy or desperate, the voice of someone who has had a little joy and wants more of it. If the person is absent, the commands become a kind of prayer. If they are present, they read as teasing and affectionate. The poem leaves the choice to the reader, and each reading changes the emotional weight of that last "again."
The poem is also notable for how little it spends. Nearly every word is a single syllable, and there is no metaphor beyond the two verbs, yet it gives a complete emotional situation: a person, a pleasure, a longing. It shows that compression can be a form of intensity. The poem takes seconds to read, about as long as a laugh or a smile lasts, and its ending practically invites the reader to go back to the beginning. Reading it twice means doing what the speaker asks for, so the form turns the reader into someone who also says "again."
For a student, then, "Smile" is a good example of how much a poem can do with repetition and restraint. Leaving things out, like the identity of "you," the reasons for the joy, and any decoration, makes room for the reader's own experience of loving someone's laugh. Anyone who has asked a friend to tell the story one more time, or wished a good moment would repeat, will recognise the feeling at once.