Mood is difficult to define for any given work given mood in a subjective topic. Any text appeals to the emotions of any reader on different levels. Mood, from the Hunter College Glossary of Literary Terms, is defined as:
the atmosphere that pervades a literary work with the intention of evoking a certain emotion or feeling from the audience. In drama, mood may be created by sets and music as well as words; in poetry and prose, mood may be created by a combination of such elements as SETTING, VOICE, TONE and THEME.
The poem evokes a feeling of hope. The poem seems to be about a new parent telling their child about the wonders of the world. The stanzas are set out in a particular way which shows the "things" that are closer to home, first, and then expanding beyond to the world outside. The parent seems to be hopeful that the child will learn all that they need to know about the world from them only to come back to the parent in the end. Therefore, the mood of the poem evokes a feeling of hope for the reader.
You begin this way:
this is your hand,
this is your eye,
that is a fish, blue and flat
on the paper, almost
the shape of an eye.
This is your mouth, this is an O
or a moon, whichever
you like. This is yellow.