Actually, I just want to point out if you've had any training on how to run a training session, you ought to know that asking "do you understand?" is pointless in every culture. From an asian culture it can even come across as threatening and dominating. Its like asking "do you want to keep your job?". Who is going to stand up and say "actually, no I don't" to that? Work in a western company is often the very first time in peoples lives where voluntarily admitting you don't know something doesn't carry significant penalties.