my little one is trying- we really like the Lion Brand size 10s for kids- short, with little kitties on the ends.
I would make sure she is using a sturdy yarn, that won't split. (Mom gave us a stash of cotton yarn bits that are great.) Something like SImply soft might work too.
We go Veeeeeery slowly. I do a stitch or two at the beginning of the row. kid sits in lap, does a few stitches, gets bored, gets off lap, chases cat around room, gets back in lap, knits a few.
I finish the end of the row and turn the needles.
I always repeat the rhyme each time I do it and each time she does it. (we are only doing knit stitch now)
I had cast on about 20 stitches and we just go back and forth. eventually it might be a coaster for Daddy.
Patience and repetition are key. But if it doesn't "take" let her take a break for a while (weeks, years) then try again. I had no ability or interest until after I had a kid. my Mom is a very talented knitter and was dying to teach me, but I just wasn't ready.
Oh- also, I don't worry about mistakes right now. if we drop or add a stitch, who cares. if the yarn is a little twisted, so what? Only if she gets it totally wrong do I worry about it. What would Dr Phil call it? Succsessive approximation. A little better every time we try. It can be hard not to want to fix her mistakes every time- but there is time for that later.