Final answer:
The nurse is assessing the psychomotor domain of learning when having the patient demonstrate how to perform self-injections of insulin.
Step-by-step explanation:
When the nurse has the patient demonstrate how to perform self-injections of insulin, the nurse is assessing the psychomotor domain of learning. The psychomotor domain of learning refers to the development of physical skills and coordination through demonstration and practice. In this case, the nurse is evaluating the patient's ability to physically perform the injection technique.