Question: clean dirt and debris out from underneath fingernails.
Options:
using a nail brush and warm soapy water, lather your hands up and wet the nail brush with warm water and brush perpendicular to the nail plate so the bristles get underneath the free edge of the nail, then rinse and dry hands.
using a nail brush and warm soapy water, lather your hands up and wet the nail brush with warm water and brush the top of the nail plate so the bristles stay on top of the free edge of the nail, then rinse and dry hands.
Answer: using a nail brush and warm soapy water, lather your hands up and wet the nail brush with warm water and brush perpendicular to the nail plate so the bristles get underneath the free edge of the nail, then rinse and dry hands.