Answer:
The concept that best describes when a child's chronic toothache interferes with their thinking and school performance is known as the "Biopsychosocial Model". This model explains how physical health, psychological factors, and social environment interact to influence a person's overall health. In this case, the chronic toothache is a physical health issue that can lead to difficulty thinking, mood swings, lack of focus, and difficulty performing in school due to the pain and discomfort it causes. This illustrates how physical health issues can not only impact physical health but also affect mental and emotional health and performance.