For a number of years I was a guest speaker at the translation faculty of Maastricht's Zuyd University. I gave a presentation (which I developed myself) to first-year students about how to write proper instructional text, and then did a question-and-answer session afterwards.
I also gave a workshop on the same subject (instructional text is what you read in user guides and reference manuals) to a group of writers and editors in Utrecht.
I am currently (spring 2017) developing the content for a workshop I intend to give to companies and educational institutes on how to write effective English.
During a six-month stint in Taiwan I taught English extensively. Those I taught it to ranged from kindergarten children (!) and schoolkids to adults and business people. Most of the teaching took place in language schools throughout Taipei, although I gave private lessons as well.