The poem begins with the speaker reminiscing about her childhood, when she and her siblings would "run riot"—that is, run around wildly. The use of the phrase "run riot" is hyperbolic, or exaggerated, and meant to illustrate the juxtaposition, or contrast, between the children's carefree existence and the mother's "quiet despair." It immediately signals to the reader how overwhelmed the mother must have felt trying to care for five children.
The use of the word "riot" also allows for an internal rhyme between "riot" and "quiet," putting added pressure on the relationship between the children and the mother, between their innocent rowdiness and the distress that comes with knowledge and responsibility.
The poem immediately introduces a bit of tension through its use of meter as well. The first line is in perfect iambic pentameter, meaning that it is composed of five iambs (feet with an unstressed syllable followed by a stressed syllable):
"When I | was young | and there | were five | of us,"
Iambic pentameter naturally infuses the line with a sense of balance and harmony. There is an idyllic quality to the speaker's remembrance, as if she quite enjoys thinking about her childhood. The second line, however, contains 13 syllables, disrupting the balance established in the first line. Because the line still follows the unstressed-stressed pattern of iambic pentameter, however, there is a sense that the line is attempting iambic pentameter but falling short. This echoes the imbalance between the children and the mother, their chaotic energy and her despairing state. The line enacts a sense of things getting away from her, but there is still more of a sense of control than not—the meter doesn't fall apart completely, the line just goes on a few beats too long.