Co-worker who is not really technically-minded approached me to discuss emailing encrypted files to a work contact (the files contained confidential data and cannot be sent “in the clear”). Anyway, taught her about public-key encryption and, specifically, how to use GPG (GNU Privacy Guard). She quickly grasped the concepts of how public-key encryption works, specifically issues surrounding key management and also the idea of a web of trust.
A pleasant surprise to find someone (a) willing to learn and (b) having the intelligence to take it all in.