Final answer:
The nurse should teach parents to report bradycardia as a sign of overdose when a pediatric client is taking propranolol, a beta-adrenergic blocking agent.
Step-by-step explanation:
When a pediatric client is taking the beta-adrenergic blocking agent propranolol, the nurse should teach the parents to report bradycardia as a sign of overdose. Propranolol is a beta blocker that works by slowing down the heart rate. Overdose of beta blockers can lead to excessively low heart rate, which is called bradycardia.