It is important that you won’t continue your training presentation past a point that your audience reached a limit of the information that they can handle. If your audience has gone through a number of days of training and you are getting towards the last session on a Friday afternoon it is wise to consider to what extend this session will be really meaningful.
You can try all kind of different techniques to grasp the attention of your audience, but there is a point that it is enough for your audience and whatever you will try, the information that you try to bring across will not land and be remembered. It is good to not get to this point as you will be wasting the time of your audience and your own time. In this case it is better to continue your presentation during another day.
Even though your audience may look at you, you don’t know if they are actually listening. Ask probing questions during your presentation, look carefully at body language to get a good idea of the state of mind of your audience. Also do some research about what your audience has done before your presentation. Use all this input to see how much valuable time you can have with your audience before the disconnect and whatever you tell to them will not have an impact. Make sure that you know when it is time to stop your training presentation.