I've gone to two. At the first one, they tried to put me at a table with 4 other pre-dents, taking patient records and filing them. The table needed two people at most. So I wandered away, started helping a dental student unpack x-ray gear from his school, and ran the Nomad cordless x-ray the rest of the day.
At the second one, they were separating the pre-dents to be 'runners' for the dentists. In other words, when the dentists needed materials, the pre-dents would run to the central dispensary and retrieve supplies. I latched on to one of the only dentists there doing root canals (most work is extractions, not preservation). I did that because he said he would be without is typical assistants. So, I got to be chair-side across from him for the whole day, helping him out.
Moral of the story: dont be afraid or meek. Just hop right in there and help where needed. As organized as they are, little things can tend to be overlooked. -Like no one specific signed up to run the Nomads, or the endodontist not having assistants lined up.
Also, I was not prepared for the number of 'thank you's that I received. Very rewarding weekends, and both of mine were 3 hours away (very much worth the drive).