I haven't read all the responses, but I wouldn't make her practice. I started piano lessons when I was very young, and by the time I played an instrument in school it was intuitive and very easy. I never/rarely practiced and was first chair through high school, when I quit as a junior so I could just do piano. Especially at her age, they're probably just learning notes, and how to hold the instrument. It probably doesn't take any time to keep up with someone who is not familiar with music at all.