Equality means that the expressions on both sides of an addition equation represent the same whole, so a missing addend or number can be determined by comparing totals, using related addition and subtraction facts, and reasoning about equivalence. The equal sign does not mean “the answer comes next”; it expresses a relationship that remains true when both sides have equal value. This work is limited to whole-number equations within 100, not generalized symbolic algebra or equations involving larger or more complex numbers.
An addition equation is balanced when both sides have the same total. The equal sign means “has the same value as,” not “the answer comes next.”
Example:
Step 1: Find the total on the side without the box.
So the other side must also equal :
Step 2: Find the missing addend.
Ask: “What number plus makes ?” Use the related subtraction fact:
So the missing number is .
Step 3: Check that both sides are equal.
and
Therefore:
Both sides represent the same whole, , so the equation is balanced.
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