Kids and dogs can be great buddies if they were introduced correctly and be trained to treat each other with respect.
On top of my other post about understanding Dog Gestures and Languages, here are two excellent posters explaining how kids should and should not interact with dogs. Very different than human, dogs uses other ways to communicate their signs of stress and aggression with each other. For example looking straight into their eyes or padding their heads can be viewed as aggressive behaviors. Most dogs hated to be hugged or kissed by strangers, as putting a face so close to them is threatening. Also, the golden rule of thumb is to wait for the dog to goto you (or your kid), rather than to chase after the dogs.
Credit of these posters goes to Dr Sophia Yin. There are lots of useful training materials on her site.