Former professor wants an update to write a recommendation letter, should I include a bad grade? I studied physics and computer science as an undergrad, got a master's in computer science, and now am applying for a second master's in engineering physics. So, I have emailed one of my old physics professors for a recommendation letter.  He agreed to write one, but has requested more information to do so seeing as though I haven't been in touch since I went to grad school. He didn't specify any particular items, but another letter writer has requested my statement of purpose draft, coursework/research highlights, resume, and unofficial transcripts, so I'm assuming he'd appreciate the same. Because he is from a different school and department and hence unfamiliar with their curriculum, I was planning to send a list of my grad school classes and grades with descriptions included rather than the unofficial transcript which only includes the course number and a brief, generic title.

I'm happy to oblige, except for one thing: I failed a class in grad school.  This is explained by a medical situation at the time; I took the next semester off, it is since resolved, I did well in all my classes afterwards, etc. - it is a non-issue now.

My question is, should I include this black mark when I send him materials? It is not something that affected any of my work in undergrad and will not affect anything in the future, so I'd think it's not really relevant. I'd rather not tell yet another person about how I failed a class, especially someone who I haven't talked to in a while and have asked to write good things about me.
I would err on the side of being honest, as you have a legitimate reason for why one specific class was an issue. Whereas that is explainable, it would be a mark against your character if he discovers that you did not give him a complete list of a classes after he requested it.