Final answer:
The preferred technique for inserting an OPA into a small child's airway is the tongue-jaw lift method.
Step-by-step explanation:
The preferred technique for inserting an OPA (oropharyngeal airway) into a small child's airway is to use the tongue-jaw lift method. To do this, place the child in a supine position and tilt their head back slightly. With one hand, lift the child's jaw upwards while using the other hand to gently insert the OPA into the mouth, following the natural curve of the tongue until it reaches the back of the throat. The OPA will help to maintain an open airway and prevent the child's tongue from obstructing their breathing.