Second-grade students are sorting drawings of objects according to whether they are symmetrical or asymmetrical. The activity can best support students' understanding of which of the following principles of art?

Contrast refers to the difference between elements in art, such as light versus dark or large versus small. While asymmetry can create contrast, the sorting activity primarily focuses on symmetry rather than differences between elements. Thus, contrast does not correlate directly with the students' understanding of symmetry and balance.

Movement in art guides the viewer's eye through a composition. While asymmetrical designs can create a sense of movement, the activity of sorting symmetrical and asymmetrical drawings does not explicitly teach students about movement. Instead, it emphasizes the understanding of balance in relation to symmetrical forms.

Unity refers to the cohesive quality that makes an artwork feel complete. While both symmetrical and asymmetrical designs can contribute to unity, the sorting activity is more about identifying symmetry itself rather than exploring the overall coherence of a composition. Thus, unity does not directly relate to the primary focus of the sorting exercise.