you have to know your major rythems and of course, your lethal rythems ( i think i am spelling that wrong, it looks weird) At my hospital ,they give us the books ahead of time so we can study. you should know vfib. vtach, sinus rhythem, asystole, ventricular standstill, etc... go through the book, brush up, practice with the cd so that way when you get to class you already know the basics. you won't have to pull out your callipers, they should be easy enough to identify so you can eyeball it and say "hey this is vtach" i do believe you need to know heart blocks too. hope that helps!