Create a "Parking Lot"
Explain to participants that the parking lot is a place to put questions, comments or concerns that are important but slightly off the topic currently being discussed. Assure them everything in the parking lot will be addressed by the end of the training and keep your word, revisiting the parking lot as appropriate throughout the training.
After the trainer has set the stage for how the group will move through the training together, she or he can then move into the icebreaker or warm-up activities. Using Icebreakers and Energizers describes these in more detail.