Tempo and General Impression

The author's score only indicates "brightly" (あかるく). Although there is no tempo marking, when the author performed it, a tempo of quarter note = 150 was desired. If it is too slow, the piece will drag.

Conceptual Approach

The concept behind this piece is that of a "dialogue of words" (ことばの掛け合い). Assuming this, it would be ideal if the speed of natural speech and the music align. One might imagine two children, with each singing the treble clef and bass clef parts respectively, or consider the idea of alternating the singing every two measures. In that case, the last two measures would be sung by both simultaneously.

Dynamics

Furthermore, since there are no dynamic markings, let's consider them with your teacher. For example, measures 1-2 and 3-4 have exactly the same rhythm and notes. Therefore, in this case, try making the dynamics of one of these measure groups either louder or softer than the other. The exact same situation occurs in measures 5-6 and 7-8. Let's also vary the dynamics here. Dynamics can be considered subito, or for instance, the final section (measures 9-12) could have a crescendo towards the end. The goal is to convey a sense of mutual understanding or agreement.

Articulation

Next is the matter of articulation. In the author's score, a slur is written in measure 1, between beats 2 and 3. It is also written in measures 5-8. By adhering to these, a nuance closer to speech might be achieved.

Key Point

In any case, the key is to play it lightly and joyfully.