<p>(I am still only in high school and do not have any experience in this; everything I have written is only my impression from these forums)</p>
<p>I previously asked something along those lines, and someone who was admitted to Caltech (I forgot his name) had told me that he had no qualifications or awards, and the only thing he had done was an extra course in maths or physics outside the normal curriculum.</p>
<p>On the other hand, I’ve also heard (somewhere on these forums) that Caltech is verging on openly recruiting Intel/Siemens finalists, and that those competitions are very likely to get you acceptance (though I can’t vouch for the truth in that).</p>
<p>The impression I get from this is that, although you don’t necessarily need participation in high-profile science competitions to get in, it helps a LOT. But, thankfully, recognition in those competitions is given to only a handful of people, and I would expect that a significant amount will be going to big-name universities like MIT/Harvard/Princeton/Stanford (surprisingly, not many people have even HEARD of Caltech). So it would seem reasonable that doing a lot of small things (pursuing hobbies like making things, even pointless things, or multiplying random 6 digit-numbers in your head when you get bored, which really isn’t as hard as it sounds if you work your way up) should give you a realistic chance.</p>
<p>But to answer your question, I would assume that you should write your essay about something you have done AND list that as an extracurricular (unless I’m mistaken, you can even list hobbies - they don’t have to be ‘official’ ECs).</p>
<p>I apologize in advance for any ignorance or stupidity I have displayed, and for my excessive use of parentheses; hope this helps =).</p>