I'm always a little taken aback by the "art versus science" debate since I think there's an implication that one is learned and one is inherent, when in reality I think both art and science are a little of both. Which I guess is also how I approach teaching. I think that there are inherent qualities that make someone an excellent teacher. An ability to read your audience, patience, and a natural knack for communication are a few of these qualities. That being said, I also believe that having these and more qualities isn't enough to make someone a good teacher. A good teacher will also have done their research on how different students learn best, what different ways to assess student's work is, and how to organize a lesson plan. Skills like these I believe are learned, not inherent. Also, teachers in public K-12 settings particularly have to have some understanding of the curriculum guidelines of their specific state, and also know how to best "teach for the test" - while this might not be a positive, there's still no doubt that governments are judging teacher quality on standards assessment, so a "good" teacher needs to be aware of what these standardized assessments are and can't just rely on creative lessons and good rapport with students to succeed.
So I guess ultimately I think the best teaching comes from inherent and learned skills. I think teacher librarians have a little more wiggle-room as they're often not faced with the same students day after day, and can be a little more flexible with lesson planning and engagement with the students. There are two sides to this - on the one hand, I think this is why so many school libraries are facing closure - it's difficult to assess a libraries effectiveness in K-12 education. On the other hand, when a library is supported by its community (including parents, teachers, students, and board of education) it can be a place where students and teachers can really think outside the box and collaborate with librarians on projects that supplement the "standardized" educational experience.
