This is our simplest tip and one that is probably the most significant in terms of improving dog/child relations. Teach kids that they should invite the dog to come to them, and if the dog declines the invitation, then they leave the dog alone.
Dogs say yes, by coming over, being loose and waggy and staying around without restraint. Dogs say no by turning away, walking away, yawning, licking or flicking their tongue out, showing a half moon of white in their eye, doing a big shake off, or being tense and stiff.
Here is a fun video from dog/child relationship expert Madeline Gabriel that shows kids how to be a kid a dog feels safe with and shows parents how to teach kids how to invite a dog to interact.