This would make a great procedure (Harry Wong). Count to five or hold up one finger at a time when the class needs to refocus. Discuss what occurs for each number at the beginning of the school year and eventually the reaction will be automatic.
an 8 x 11 sized "poster" created to help my second grade students to remember to write better sentences. It helps them to remember to include details in their sentences and try to paint a picture with words, including verbs, adjectives, nouns, etc.