Final answer:
The nurse is using the pain management technique of distraction.
Step-by-step explanation:
The pain management technique being used by the nurse is distraction.
Distraction involves redirecting the patient's attention away from the pain and towards a more pleasant stimulus, such as music, to help alleviate pain and discomfort. In this case, playing music for the child with leukemia is a form of distraction and can help reduce the perception of pain.