Couldn’t find your reference in person, but need to ask for one? Here’s an email template to help get you started. Personalize the email by replacing all the generic text with your information. 

Email: Professor's email address

Subject: Request for Strong Academic Reference

Dear Professor X,

I have really enjoyed the classes I’ve taken with you over the past few years. I took CLASS X and CLASS Y in SEMESTER YEAR. I particularly enjoyed THIS ASPECT OF YOUR CLASS. I tried to touch-base with you a few times this week in person, but unfortunately I was unsuccessful.

I am contacting you because in your class I was able to develop [THESE SKILLS/KNOWLEDGE BASE/DEMONSTRATED EXPERIENCE WITH] and I am hoping that you will be able to speak to these in a reference letter.

I am interested in studying [TOPIC] and am applying to the following programs:

1. [PROGRAM] at [INSTITUTION] for [insert specialization if applicable]
2. [PROGRAM] at [INSTITUTION] for [insert specialization if applicable]
3. [PROGRAM] at [INSTITUTION] for [insert specialization if applicable]

Please let me know if you feel you would be able to provide me with a strong reference. I understand if you are not able to and appreciate your time.

I would be happy to discuss my applications with you in more detail in person at a time that works with your schedule.

Looking forward to hearing from you,

[Name]