I absolutely LOVE doing Mystery Skype in my classroom! I have found that using these dialogue cards to communicate with the other classroom has been extremely helpful. We use them to let the other class know when we are ready, when it is their turn, etc.
Simply print on card stock - I did different colored card stock, and that's it! Don't laminate because the glare makes it hard to read via Skype.
Dialogue cards included are:
We're ready for your question
Thank you for working with us. We had fun.
We're in ________ (fill in your town, state, etc.)