May I suggest NOT letting your child walk the dog? Please. Any child under 12 should not hold the end of a leash. And they all want to. I know they do. Parents will need to explain to me why kids want the leash so badly.
Small dogs shouldn't be at the whim of silly kids. Small kids shouldn't be at the whim of large dogs. It's hard for someone not to get hurt--and to make good choices. Even kids who are 9 or 10 do some dopey things--like bring their dog over to visit another without knowing if the dogs will be friends.
It's FANTASTIC to give responsibility to children. They should definitely feed their dog; they should ask the dog to sit; they should play hide-and-seek with her; they should work on recall with their sibling and the pup "monkey" in the middle. But not walking. Leash handling is hard enough for adults, let alone young-uns.
Having said that, I sometimes see a fantastic 4-year-old girl run her Westie in agility trials! For real! Adorable. Junior handlers are all over the dog world. But they take special guidance in the training process and the dogs have to be special, too.
One more point: let's all work on teaching children to "be a tree" around dogs they don't know: stand still with arms at their sides. You can't blame dogs for being tentative around kids when so often they are unpredictable and loud and erratic. They flail around and stomp and scream and run up to dogs. One little boy in my neighborhood--he's probably 4--actually comes over and on his own stands very still for my dogs. He will even kneel down on the sidewalk so he and Tanner can kiss each other. He innately knows or has been taught that he's taller than toy dogs, so he makes his tiny self even smaller. So sweet. I love his dad!