Here's how it works:
Each morning I introduce the Word of the Day. We discuss the meaning of the word and how it can be used in different sentences.
The students know that when it's time to transition they're not allowed to move until they hear the Word of the Day. For example, when changing from Math to Language, and if the Word of the Day were voyage, I might say something like this:
"I'm looking for whole body listeners.
(Proceed when you have everyone's attention)
When (emphasize when in the beginning)
you hear the Word of the Day
I'd like you to clean up your math practice
and have your language books open to page 125.
The word of the day is voyage."
Later I might ask for the definition of the Word of the Day prior to saying the word. Or I might say, "Today's word of the day means a long trip or journey. The word is____." The students will fill in the word when I pause.
Here is a FABULOUS video from Teaching Channel where Ms. Noonan shares how she uses the Word of the Day and some other cool ways to manage transitions.