Gluing the spine

I work at a university library and I know a fair bit about book binding. I was asked about my skills & interests and I mentioned this. My manager asked me to run a class for 5 other staff members about book binding & mending. After the class, all the attendees keep on making the same mistake. They glue the spine to the outside cover. We've tried ore training and explaining but nothing seems to work. They don't get it.