Final answer:
A school nurse performing a Rinne test should instruct a student by placing a tuning fork behind the ear and asking when the sound is no longer heard; the test helps to distinguish between conductive and sensorineural hearing loss.
Step-by-step explanation:
When performing a Rinne test, which is a method to distinguish between conductive hearing and sensorineural hearing loss, a school nurse should provide the following instructions: "After I place this tuning fork behind your ear on your mastoid process, tell me when you can no longer hear the sound." Once the sound is no longer heard, the nurse would then immediately move the tuning fork next to the ear canal to check if the sound is heard through the air. If the sound is not heard, it might indicate a conductive hearing loss. This test compares air conduction (hearing through the air) to bone conduction (hearing through the vibrations in the skull).
The nurse should ensure that explanations and instructions during the hearing screening are clear and understandable for elementary school students, adapting the language and approach accordingly to their age and comprehension level.