ARe supplements with 250 word limit supposed to be an exercise in creative writing or just show your research into your major and interest in the school?
If possible, visit the school. That will give you the most personalized answer. If not, research the heck out of the school including official YouTube videos and answer how the schools fits you and will help you achieve your goals.
@TulaneJeff has a good blog on how to approach these statements.
http://tuadmissionjeff.blogspot.com/2013/09/the-optional-statment.html
The college wants to know why you are interested in it specifically (versus other schools that may superficially share some similar characteristics). This can be especially important if you are “overqualified” for that school and may appear to be using it as a “safety” behind a more selective school that superficially shares some similar characteristics.
Sportsman88, TJeff says it well, good link.
OP, it can be casual, this isn’t the place to rattle off a long list of classes you’d take or titles you’d get in activities. Nor how it will prepare you for your dream career. If you know the school well enough, and how you fit what they want, it should be a breeze. So just settle in and think about it.
This is not the spot for creative writing. They earnestly want to know where the match is for you and the school. If you can’t visit, carefully peruse the website. My kids talked about specific courses that appealed to them, clubs they wanted to join, and research facilities or labs they hoped to work in. It did help to have been to campus. From visits, they would sometimes mention something out of the way they saw on campus (one talked about sidewalk chalk signs) or a class they sat in on. I believe one of my kids may have mentioned excellent coconut cake in the cafeteria. 
Intparent, I think we can say your kids showed a connection, nothing generic about their responses. Super.
As stated above, for these supplements they’re not looking for a creative story, they just want to see how serious you are about this school. Are you applying because you’ve researched what the school stands for and truly want to attend that school, or are you applying because you figured why not and you haven’t really done your research. I recommend you research the campus (ie go on the website, do a virtual tour, etc) and find things about that school that really stand out to you and make you want to go there.
I can’t imagine that any school would assign an essay, and the manpower to read each of those essays, if it didn’t have some real value.
They’re giving you the opportunity to show why they should pick you over someone else. Don’t waste that opportunity. They know you’re applying to 8 or 9 other schools— let them know why you would choose their school.
Some good advice here too:
http://talk.collegeconfidential.com/college-essays/1705515-some-help-with-why-this-school.html