In addition, they should sit, buckled in, every second that you are. No wandering back to business for half an hour. And if we really want to make it realistic, have them answering super simple questions on an iPad app non stop while airborne every thirty seconds for the entire journey. Ie 1+1 = ? Then thirty seconds later what is the opposite of up? And if they miss one get them to turn up for tea and bickies to explain themselves. By the end of the second day they will be starting to rethink things I reckon.