My host parents had a rule not to feed the kids with leftovers (actually not to keep leftovers). That was a very big surprise for me because in my country we think that is a waste of food and I would normally use leftovers to make a different dish. When we talked about it and my host parents understood my point, we made a deal that leftovers can be eaten if they were in the fridge for just one day, no more! It was good that we talked about it because it helped me be open to their concerns and accept their thoughts, too.