What is needed to write a lesson for publishing.....

Have you ever created an article in hopes it would be published in School Arts or Arts and Activities magazines? If you have, tell me what you believe is pertinent information to have in your article to get it selected. I am thinking about submitting an article but do not want to go through the trouble or effort if it might not be picked! Let's be honest ya'll "who's got time for that?" So in the comments below please tell me what you think is important to selection and if I get picked I will give you props on my blog :) Thanks in advance!