In William Wordsworth's poem "We Are Seven," how does the author create eeriness at the beginning of the poem?

The poem "We are Seven" is about an eight year old girl
who is playing among the tombstones in a graveyard, and the poet observes how happily
she plays and with how much energy she is invested in her playtime. When he asks her how
many siblings she has, the girl insists in that there are five alive and two are in the
churchyard (buried). However, she insists in that they are still seven total. This is
indicative that the little girl's innocence prevents her from differentiating the pain
of death from the joys of life: She is joyful regardless because she represents the
innocent aspect of childhood and joy.

Wordsworth does,
however, use a bit of eeriness in the beginning, because the poem begins with a sudden
application of contrast in the play on words

A
Simple Child,
That lightly draws its breath,
And feels its life in
every limb,
What should it know of
death?

Wordsworth began his stanza using childhood
in the first verse, and death on the last verse, making the stanza contradictory and
contrasting in that childhood and death should not go together in one same thought, and
thus provoking a sense of eeriness. This is indeed an effective technique because the
contrasting quality of both terms bring the reader to suspect that something will occur
in the poem that will equally result in irony and even sadness.