This advice is not timely now as most of you have submitted your applications long ago, but here goes anyway.....Most applications, scholarships, etc have some space somewhere for comments. If you have something, like marciemi's son's Academic Decathalon, that you desperately want to expound upon, get it in there. Or somewhere in that application.
You have asked some teachers to do recommendations for the SA you are applying for........provide them with a resume and even a copy of your application. Tell them you have something, like the Academic Decathalon, that you feel is unique and there is not really a place on the application to express the amount of time, commitment, dedication, etc you have given to that activity. Ask if they could mention it.
When you get ready to do any type of application, read the criteria, the key words, ie: what is the selection committee looking for? Next, list why you want or feel you qualify for whatever it is you are applying for. If there's no space on the application for your activity or unique quality, find a place to get it in there: the places where they ask for more information (you wouldn't believe how many folks leave those things blank), the essays, the letters of recommendation, etc.
Even if your activities are listed and you can check them off: President of Senior Class, etc, ALWAYS, ALWAYS tell the committee more about the position....... "As President of NHS, I organized four teacher appreciation days, baking 9000 cookies......." Lots of these "leadership" positions are simply popularly elected and somewhat figurehead type positions. If you actually did some good stuff, make sure the committee realizes that!