If in school you were less than verbose in your paper writing, your teacher might have admonished you to grow your vocabulary. She would have explained to you that as you get older, you will need more words to name and describe things you wish to write about. She would have been kind and likely would have given you pointers on how to go about such an endeavor. She never would have raised her voice or chastised you about your lack of words. To admonish someone is to encourage them to do something better.
Admonished defined: 1 a : to indicate duties or obligations to b : to express warning or disapproval to especially in a gentle, earnest, or solicitous manner 2 : to give friendly earnest advice or encouragement to--Merriam-Webster.com