Final answer:
After positioning a resuscitation mask on a child, the next step is to seal the mask on the face, then open the airway before blowing into the mask.
Step-by-step explanation:
When using a resuscitation mask to give ventilations, after positioning the mask over a child's face, the next step would generally be to seal the mask to prevent air from escaping. To do this effectively, ensure the mask fits snugly over the face covering the nose and mouth. Using your hands to create a tight seal, you would then open the airway by tilting the head back and lifting the chin. Once the airway is open, you would proceed to blow into the mask, delivering breaths to the child. It's important to note that prior to ventilations, it's essential to call for help and assess the child for responsiveness and breathing.