Let trainees find solutions for their problems themselves. Benefit from swarm intelligence.
At the end of a training block each trainee writes one open question on top of a sheet of paper. She hands the paper to the person on her right (and receives one from her left). On the sheet she receives she reads the question ans writes down any idea/ answer she might have She adds her name for any clarification questions. If she has no idea or answer, she hands the sheet to the next person.
Afterwards everybody hands the sheet to the person on her right … The exercise ends when everybody has her original sheet back.