Just be yourself and tell them why you want to work with kids. If they see your passion you shouldn't have a problem. I went right into pediatric Hem/onc when I graduated. I knew it was the only place I wanted to work and they had a great training program for new grads.
I am now returning to the same position after 16 years away to raise my own girls. I never imagined they would even talk to me let alone hire me. I had one interview and they offered me the position. I feel like a new grad in a way, but I also have the previous 5 years of experience on the floor. I know I have a lot to catch up on, but I am so happy to be going back to my passion.
If you just tell them why you want to work with kids, I don't think you'll have any trouble.
Good luck. Let us know what happens.
Karen