write down to
write down to (one)
To write in a manner that is insultingly condescending to the reader; to write as if the reader or readers are less mature, intelligent, or capable than they really are. I love this children's author. She tells beautiful stories that resonate with kids, while never seeming to write down to them. I hate the way the boss writes down to the employees in his memos.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
write down to someone
to write to someone condescendingly. You should never write down to your audience if you want to be convincing. I have to write down to them, because they are very young.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.