Final answer:
During a chart reading for an eye exam, a child should cover one eye at a time to assess each eye's visual acuity individually.
Step-by-step explanation:
When a child is reading a chart for an eye exam, the correct protocol is to cover one eye at a time. This allows for accurate assessment of each eye's visual acuity individually. The traditional practice of chart reading in vision screening or eye examinations dictates that the patient covers one eye while reading the chart, then switches to cover the other eye to ensure both eyes are tested. It is not recommended to cover both eyes or to read without covering the eyes, as this would not provide individual eye assessments. Alternating the eye that is covered can help compare the vision of both eyes.