What's most valued in a class?

With all the end of the year surveys being sent out to us and conversations I've had in the past few days, I have really started to wonder what are the most important things about a class. What makes a class meaningful? Rigor? Structure? Opportuity for discussion? A good professor? Content? I don't know what the answer is, but my guess is that maybe it's a combination of at least some if not all of these, plus a few more. However, I think the most important feature of class is not necessarily what it makes you think about, but how it makes you think about it. Some classes challenge students to deeply think about how they view the world and themselves, others require students to think about the applications of the taught concepts. Both are valuable (props to the liberal arts education!). If I look back at the past three years of college, my best classes were the ones that challenged me start to think in a different way. They made me think about why I had some of my opinions- why I thought what I think, why I believed what I believe. These classes had little common ground in terms of curricula or even how the curricula was taught, but they all challenged me in some way or another about my way of thinking. These are the classes I will remember. I won't always remember the grade or the exams I stayed up all night studying for or what the exam was even testing on. But why I liked the class- that I will never forget.