You should only write something in the “Additional Information" section if you have something to write. Okay, I know that sounds obvious–maybe even a tad snide–but your question is actually a good one.
Admission officials can be pretty cranky by the time the clock is nearing midnight and they've got another seven folders to finish before bedtime. So use their time well … or not at all.
If you believe that there is an important explanation that needs to be part of your application but isn't covered elsewhere, you should certainly use “Additional Information" to tell the college people what they need to know. But never feel as if you MUST use that section. Leaving “Additional Information" blank is not at all the same as skipping an optional essay. (Those persnickety “Optional" application essays usually aren't all that optional!)
Good reasons to complete “Additional Information" vary widely. They include:
-Irregularities in course selection or grades … but only if they are truly irregular.
-Major obstacles (e.g., serious medical problems, death in the immediate family)
-Atypical extracurricular undertaking that requires more space than the application activities section allows
-Atypical home life
-Frequent moves or school changes
This is not a complete list. There are certainly other reasons—some perhaps unique—that might spur a student to share several hundred extra words with admission officials.
But avoid discussing hardships that really aren't all that hard (“I had to share a room with my noisy little sister for a month while my own room was being remodeled") and don't sound whiny or petty (“I got the worse calculus teacher this year, and my A- would have been a A if I'd been in the other section).
I know it can be frustrating to feel as if strangers are making critical decisions about you based on the limited data that a college application conveys. And sometimes, when those applications feel just a little too limited, the Additional Information section can be the perfect place to say more. But use good judgment. Think about those weary, bleary admission folks before you start supplying any Additional Information, and rest assured that you are not expected to use that section at all .