Ask students if they can think of other types of balance: texture and no texture (smooth), size and scale, elements of a composition.
The rectangle has three lines of symmetry: Horizontal (blue), Vertical (red), Diagonal (yellow). The triangle has only one line of symmetry: center or, in this orientation, Vertical. You can draw two other lines of symmetry from any of the vertices to the center of the opposite side.
INTRODUCTION TO GRAPHIC DESIGN MOVEMENT, BALANCE, UNITY, CONTRAST, EMPHASIS, LINE, AND COLOR