You are doing a terrific job if the kids are enthusiatically directing the discussion. My rule of thumb: Limit teacher talk to 5% of class time. Students will learn more when you elicit questions from them, or have them engaged in doing something real, like singing or playing or reasearching. I love setting kids up with a controversial--perhaps dangerous--issue, hinting at it, alluding to it, teasing their interest. People are more likely to learn when they can't stand not knowing something. It takes a bit of practice to deftly deliver the kinds of questions that lead to other burning questions.

If you are a new teacher, here is a technique I use with children of any age. I tell them I would like them to think about this question for 30 seconds (this gives slower students "think time"); then prompt them to whisper the answer to someone near them (some get a chance to show off, and those who don't know can acquire the information), then ask for a show of hands.