Methods can be no longer than five lines of code.
I feel like this one is always tricky for me, it has forced me to keep thinking about how to refactor more, so my code has definitely improved since when I first started at Turing, but it's still really hard for me.
Controllers can instantiate only one object.
I almost made this one my first choice, because for my personal project I had a multi-model form, and how the heck would I have not passed all those objects to the view? Then I saw her solution to that and it made so much more sense! I could have made a PORO to initialize all the objects for my multi-model form and then initialize that in the controller and send it off to the view.