when I first saw that we had to write a blog entry of efficacy, I was a little intimidated because I have no idea what efficacy means.
according to dictionary.com efficacy means effectiveness - and I do know what effectiveness means=]
I think that being confidence in yourself as a teacher and your abilities is a very important skill to have. I am a firm believer that people won't believe in you (especially children) unless you believe in yourself. Although you may feel unsure, or at times questions your abilities - you must always feel that you are capable of doing a wonderful job, it might just take a little more work.
I also think that persistence and work ethic are both important traits to have in order to be an effective teacher. I personally think that work ethic is an important characteristic to have in life, not only in teaching. If you are willing to work, and work hard - you can accomplish anything. And again with persistence, having this trait allows you to succeed. Specifically with children I feel that is important to be persistent in your expectations of each child.
As a teacher it is important to be self-aware. What are my strengths? what needs a little help? etc. recognizing that you may have to make some changes (for the better) is the first step to becoming a better and more effective teacher.