I have a student who is 12 years old and tiny, with tiny hands. She started piano young with a different teacher and came to me a couple years ago already doing rather well with sight reading but needing lots of retraining with counting and fingering. Two years later, she's doing far, far better with those two things, and seriously taking off. I would estimate she's a strong level 6.
The other day, she came to her lesson having not only perfected but memorized a few of the pieces I'd assigned her a week earlier. I asked her how much she tended to practice each day, and her answer was, "I don't know. It's summer, and I'm bored, so I practice all the time."
I need to keep this girl in music, and when she's passing it off all the time, she's gone through all my favorites and then some. Haha. She absolutely loves fast, furious pieces, especially in minor keys, as well as upbeat jazzy pieces. She's fine with sonatinas. Slow and beautiful is more or less right out, though I do assign some of those for character building. I aim to always have one or two assigned pieces that I know she'll love and practice like mad, though.
She can reach an octave, but it's kind of uncomfortable at this point. Definitely not any full 1235 chords or anything where she'd need to move her octave a lot, like playing an octave scale.
Share some of your favorite pieces that you think might appeal to her.