I got deferred from Caltech, but accepted to MIT! 
Here are my stats and some stuff from my application for those interested:
Academics & Background
Background: Male, Chinese American from a California Charter school
UWGPA: 4.0, WGPA: 4.3670 (valedictorian, or salutatorian if you include people who transferred in)
SAT: 740 R/W, 800 Math, 20/24 Essay
SAT Subjects: 800 on Math 2, Chinese, Physics, and Chemistry
APs: Chinese (5), World History (5), Calc BC & AB subscore(5), Comp Sci A (5), US History (5), Capstone Seminar (4), English Literature (3), Statistics (5), Chemistry (5)
College Classes/Online Classes: Elementary Statistics, Multivariable Calculus, Analytic Combinatorics, Linear Algebra, Introduction to Differential Equations, Threat of Nuclear Terrorism
4 Activities:
- Boy Scouts (Life Scout, Senior Patrol Leader for over a year)
- Math Club (Founder and President, I create lessons and handouts and teach interesting topics at meetings, such as number theory and geometry. I’m also the founder and coach of my school’s middle school section’s MATHCOUNTS team and this year I’m adding in our school’s ARML team)
- Web Design Club (Cofounder and Copresident, I teach members how to make websites with HTML, CSS, and JavaScript and encourage club participation at Hackathons. Our main goal in this club is redesigning our school website, which should be done by mid-January)
- Varsity Volleyball (I played on my school’s Varsity Volleyball team in junior year as the Middle Blocker)
Work Experience: Mathnasium Instructor (I’ve been working as a Mathnasium instructor since junior year, where I tutor elementary through high school students in math).
Summer Experiences: I spent most of my summers traveling, visiting family, and volunteering. During the summer after junior year I started doing math research with a professor.
Nonscholastic Distinctions: Life Scout (11th grade), Breakthrough Junior Challenge top 10% (11th grade), WINK Leader (10th, 12th grade), Voted most likely to wake up early on a weekend (10th grade), Senior Patrol Leader (11th, 12th grade)
Scholastic Distinctions: 2018 Fall OMO 36th Place (11th grade), National AP Scholar (11th grade), AIME Qualifier (10th, 11th grade), 3rd place in SrcHacks Hackathon (11th grade), 1st place in schoolwide Essay Contest (12th grade)
AMC 10 score: 120, AMC 12 score: 100.5
AIME Scores: 5 (2018), 10 (2019)
Essays:
- For the activity you do simply for the pleasure of it, I wrote about solving puzzles and riddles in my free time.
- For the essay about what MIT program appeals to me, I wrote about the development of my passion for both computer science and mathematics and how MIT’s 18C program will allow me to continue exploring both subjects.
- For contribution to community, I wrote about my experience tutoring in freshman year and how my passion for it motivated me to start math club and later work as a tutor.
- For the world I come from, I wrote about being Chinese American and having very different traditions/experiences at home compared to at school and how being in such a diverse mix of environments has fostered my acceptance and appreciation for diversity.
- For something that didn’t go to plan, I wrote about running for ASB in my freshman year and how I was disqualified from a miscommunication. I dealt with that by accepting the failure and learning from it and seeking alternatives. I ended up applying for my school’s WINK Program instead and was accepted in and since then I’ve come to enjoy that much more than ASB.
Letters of Rec:
Math teacher/club adviser: 10/10 (I feel like this was by far my best letter of recommendation. I had seen his evaluation sheet for another school before MIT and I was amazed by how positive and well-written his evaluation for me was. He also sent me a note after submitting his that it was the best one he’s ever written)
Spanish Teacher: 8/10 (My Spanish teacher’s always been really encouraging and helpful to my learning of Spanish and in general. He’s very open to giving me advice in life and everything)
Counselor: 9/10 (Even though I’ve only known my counselor for 4 months when she wrote her LoR, I’ve been one of her favorite students and she knows me really well for my passion for STEM from the awards I’ve won)
Additional Information: I included a link to my Quora account, where I’ve been posting advice and help on math, science, and standardized testing questions for over 2 years. I also attached my video submission for the Breakthrough Junior Challenge which I was super proud of.
Maker’s Portfolio: I submitted a Maker’s Portfolio containing a 3D graphing calculator program I made while taking Multivariable Calculus. It could plot 3D functions and tangent planes in a rotatable 3D space, and calculate partial derivatives, multiple integrals and surface integrals.
General Advice: Not every school’s going to be a perfect fit for you. Personally I felt a strong connection with MIT as I learned about their student culture through their blogs and YouTube channel throughout high school, and as I went through their application process. I felt that their application flowed very nicely with my overall interests and experience in high school and their essays were extremely easy to write for me because many of them fit into my ideals (such as contributing to my community and having something to do purely for the fun of it).
You should strive to get into schools you feel a deep connection to, not just for prestige, and you should really bring out this connection through the essays.