Addressing an academic weakness in your application requires judgment about when explanation helps vs. when it draws attention to something that would otherwise be overlooked.
When to Address an Academic Weakness
Address it when: the weakness is visible in your transcript and would raise questions without context (a semester of C's in sophomore year, a failing grade in a core subject), you have a genuine documented circumstance that explains the performance, and the explanation is brief and factual rather than defensive or elaborate. If your academic record is otherwise consistent and the weakness is minor (one B in a sea of A's), drawing attention to it in Additional Information may be counterproductive.
How to Frame an Explanation
Framework: what specifically happened (factual, brief), how it affected your academic performance, and what your record looks like now (forward momentum). Example: 'During spring semester of 10th grade, I was hospitalized for two weeks following an appendectomy and managed a difficult recovery. My grades in that semester reflect the disruption. Since returning to full health in fall 10th grade, my academic performance has been consistently strong, as visible in my 11th grade record.' This is factual, brief, and forward-looking.
What to Avoid
Blaming the teacher, the class, or circumstances that aren't genuinely extraordinary. Long elaborations that make the weakness seem more significant than it was. Defending your character rather than simply providing context. Addressing every blemish on your transcript — context should be reserved for genuinely significant outliers, not routine imperfection.