Thanks Slim. She weighs about 45 kilos. She likes going fast, but at the same time she's always dragging me down steeper and steeper slopes which require her to turn and control her speed. I want her to get onto her edges more, so I'm looking for a slim waist. I also read somewhere that if there are rockers, then this reduces the effective length of the ski.Shorter skis will be easier to turn, and more forgiving of mistakes like getting backseat).
Longer skis will give more stability at speed.
When you combine those two you see that:
In general, with new skiers, it’s better to err on the side of too short than too tall.
The same goes for adult (for heavier skiers) vs kids (for lighter skiers) skis.
You did not mention her weight, which, as @Jilly mentions, is more of a factor for ski size/type than height, especially for front side (on piste) skis.
I imagine kids' skis are more flexible, so I'd like to go for something designed for lighter skiers. This will also help her carve turns, won't it?
Many thanks