Lion makes very cute kids' needles with little bears on the end
I started teaching my DD when she was 4...we started with finger knitting to work on her manual dexterity. After she knit 458736923 little scarves we moved on to needles...she can cast on but sort of lost interest on the way to the knit stitch.
(She's fiercely independent and gets mad when she can't master things right away -- we're working on that and will continue to work on that for years to come, I'm guessing.) I do believe it can be done if they really, really want to learn. :D