Undergraduate / I find myself surrounded by "model students"; Common App [12]

If I have anything to say about it...I think you're going to shoot yourself in the foot if you send this in.

Your description of the "model students" seems more like a diatribe against the people who have better grades than you over anything else. You generalize them to be GPA "slaves" who "join every club they can just to get it on their record" and who "study day and night to earn perfect scores on standardized tests." That seems a little ignorant to say, don't you think? And plus it does not tell me at all that you're going to be a good fit in a community like MIT where the majority of the students there are the "model students" you just antagonistically described.

Remember: grades aren't everything. Admissions officers know that. They have enough sense not to admit students based solely on their GPA or SAT scores.

Everything after that is awesome, though, and I'm sure you can make one heck of an essay out of it if you haven't already.

Undergraduate / Olympiad training : MIT significant challenge [2]

The lectures are hard, the tests are complicated, the friends are intimidating and the lab works were stressful because the lab was small and crowded.[Rewrite: hard lectures, complicated tests, intimidating "friends" (not sure if "friends" is the best word), and stressful lab work: ] That was my first impression of International biology Olympiad training. It wasis frustrating to know that there are many people who are much better than us at what we thought arewas our strength. Still, I believed that my decision to attend the trainingparticipate was not wrong. I believed that if I tried, the training would become more enjoyable.[Either expand on this sentence or omit it.]

Just some rudimentary editing above. Essay, as a whole, is underdeveloped. It seems like you jumped from introduction to conclusion without telling about the challenge other than a passing remark that it was "stressful". You didn't talk about how you worked through the challenge.

I would completely rewrite the second paragraph (hence, the reason for no editing marks); it's way too unclear for me to grasp clearly what you want to say.