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Letters of recommendation

Sometimes high school students ask me for reference letters. (Some of them even got in!) So here are some details. Inspired by Ravi Vakil.

Programs I can write for#

I write letters most commonly for RSI and typical undergraduate colleges (MIT and Common App). For the latter, most people prefer to invite me as a supplemental letter rather than as a math teacher proper. I can also write letters for MIT PRIMES, although I am of the impression that the awards and entrance exam hold much more weight than rec letters for PRIMES (compared to, say, college apps).

I’ve also written letters for summer math camps such as Canada/USA MathCamp, PROMYS/ROSS, etc.

Whether to ask#

Letters from me will necessarily be a bit unusual, so you should think about whether I’m the right person to do this. Here are a few reasons why:

  • I am not formally a teacher or professor, which may confuse any clueless admissions officers1.
  • Also, if I only worked with you at MOP or OTIS, I may not have spent enough time with you in-person to “paint a picture” compared to a teacher at your school, so to speak.
  • You are going to be compared to other OTIS/MOP students. This is not to say the comparison will necessarily be unfavorable. However, the letter is probably not going to say you are the strongest student I’ve ever met, either, whereas many of you are the best student your local high school has ever seen.

Usually people will ask me for letters if they want to add some context about their math contest experiences that’s more than just score, or to have me advocate for their mathematical ability. I try to also, when I have enough data, say a bit about what you’re like as a person when interacting with me or other OTIS students.

Since I’m a nice person, I promise to not intentionally write a negative letter.2 If I feel I cannot write you a letter with nonnegative value, I will decline your request instead.3

Sample letter#

Here is a sample letter for an imaginary student named Eva Chan, so you know roughly what you’re signing up for. (And those of you writing your first reference letter are welcome to use this as an example.)


If you do ask a letter for me, I need the following information.

  1. Please remind me which years I worked with you (in OTIS/MOP/SPARC/etc.). I have been doing this for so long that the years are all mixed up in my head, so I’d like to double-check!
  2. Provide any recent math olympiad results, like USAMO / TSTST / TST / IMO. (I may not use them, but I want to have them if I need them).
  3. Is there anything in particular I should discuss? In particular, how math-focused do you want me to be?
  4. Please send me any application essays or completed forms you are willing to share (drafts of essays are okay). This way, I can tailor my letter to complement what you’ve already written.
  5. If I’ve written a letter for you in the past, please remind me about it.
  6. Please also specify which email address you applied to the program with.
  7. Specify what “type” of letter I am writing, if applicable. For example, colleges commonly distinguish between, say “required” letters from a math teacher, or optional “supplements” (see e.g. MIT, second-to-last paragraph). It is useful for me to know whether I am the main voice or if I am expecting to add on to what other (usually more traditional) teachers have to say.
  8. State explicitly when the deadline is.
  9. Indicate your current grade-level in your high school/college, and what year you expect to graduate.

Additional technical instructions:

  • Ideally, ask at least a month in advance. (If it’s less than one month, you can still ask, but I may decline.)
  • Requests, and accompanying materials/info, must be sent by email. Not Discord direct message. I can’t keep track of those.
  • When inviting me to whatever application the school or program uses, it’s best if you invite the address evan at
    • Exception: for some reason, (which is used by REU’s and MIT PRIMES) does not seem to work well with my professional email. You should use evanchen at there.
  • Usually, I will always submit letters at least a week in advance if you asked ahead of time. So if it’s less than a week until the deadline and the letter I promised hasn’t been submitted yet, then please double-check on it.

  1. Although I am gradually picking up increasingly fancy titles. 

  2. Regrettably, I speak from experience here. When applying to graduate school and fellowships, a sympathetic interviewer tipped me off that one of my letters was “not doing me any favors” and warned me to delete it from my graduate school applications if possible. I am still grateful to him today since I would likely not have been admitted to MIT’s math PhD program otherwise. Alas, this tip was too late for all the other schools, as I had already finalized my application at that point. 

  3. This is because I believe a good mentor should be unconditionally supportive, much like a parent, and that it’s not my place to judge students. 

Updated Fri 10 Nov 2023, 20:52:45 UTC by 4a9927a9b864