Final answer:
The nurse should ensure that older adults understand the purpose of their medications, as it is critical for proper adherence and recognition of effects and potential side effects.
Step-by-step explanation:
The nurse should ensure that the older adult understands the purpose of every medication they are taking. The understanding of a medication's purpose is essential to ensure proper adherence to the medication regimen, and to be able to recognize its effects and any potential side effects. Unlike the color, shape, or brand name, the purpose provides the patient with meaningful information that affects their health and treatment outcomes.