This site in general may not be suitable for elementary school kids. A lot depends on the kid of course, but fair warning if you turn them loose around here. If they wander onto the forum they'll likely wind up banned.
BD's profile has the link the Firefox and Chrome extensions, which will let you filter by tags. What you're looking for is "Geared for Children".
http://chooseyourstory.com/Member/?Username=BradinDvorak
Endmaster has a story called Imagination that may be a good place to start. Unfortunately the princess games by cheniepenny were all taken down..
Of course you're always welcome to write your own children's games if we have a lack of them. Although in my experience, kids who like to read learn to despise the "kid friendly" stuff we'd pick out for them pretty quickly.