The ornamental design for a balance for teaching, as shown and described.
FIG. 1 is a perspective view of a balance for teaching;
FIG. 2 is a front elevation thereof;
FIG. 3 is a rear elevation thereof;
FIG. 4 is a left side elevation thereof;
FIG. 5 is a right side elevation thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a reference showing the balance for teaching in the position of use, the broken line showing are for illustrative purposes only and form no part of the claimed design.