N93332 wrote:

See FAR 61.23. You can do flight instruction without a current medical if
the student is PIC. That would limit the training to post-private, sport
pilot, and current BFR's.

Can't do anything that would require you to also be the safety pilot in
Simulated Instrument Flight. That's a real sticky point for a CFI
friend who lost his medical.

Pretty limitted what you can do as a pilot or even an ATC without a
medical. Mechanics school is an option.