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.
**Updated - I put the attention getters into a table format**I use these Whole Brain Teaching attention getters on a daily basis with my ELL students. These attention getters are a great way to improve your classroom management. I usually pick one