Music is a beautiful gift and one that lasts a lifetime.
My grandfather was a professional musician and I began lessons at age 5 and continued playing until I left for college. Today, I regret ever having stopped. Unfortunately this is a common refrain as many preteens and teens lose interest in activities, even those at which they excel.
As each child is an individual, I recommend speaking with your daughter in a non-confrontational way to get at the root of her perfunctory practicing.
Does she enjoy playing music? Maybe she has other appropriate interests she would prefer to pursue.
Would she like to try another instrument? Although musical instruments are an investment, her school may be able to give her loaners.
Ask her if she'd like to mix up the repertoire. Classical music is wonderful but a little jazz or popular music may help her find the joy in playing.
Perhaps she enjoys piano but just cannot find enough time for studies, music, and her other interests. Help her with time management skills.
If she is goal oriented, a recital or music camp admission may focus her efforts.
Or maybe she finds practicing solitary. She could form an ensemble with other kids her age. This way some of her practice is also social and the commitment to her band mates may provide peer motivation.
If the solution comes from her, she is more likely to find internal motivation to practice more often.
My son is almost 11 and plays the piano, keyboards and organ. He has had times however, when he is gets bored and needs a break. I would see if this is the case with your daughter. Maybe she needs a break, or maybe she needs to play something of her choice...We have let our son choose certain songs he wants to play instead of what his teacher assigns. Sometimes this makes all the difference in him wanting to practice on his own without a friendly parental reminder. Hope this helps.
Interesting question. My daughter took piano from her previous teacher for a year. She learned the things the teacher taught, but after eight months she started to lose interest in piano. We hashed out another three months with that teacher and then could just not do it anymore. For one, the teacher was dull and boring, for two, I don't think she really enjoyed teaching.
After searching for a new teacher, we were blessed... I mean really blessed to find the teacher we have now. She makes piano FUN and exciting. She has introduced theory and has made it interesting. At my daughter's first lesson, Miss P. asked, "have you ever seen the inside of a piano, do you know how it works?" They went on to investigate the makings of a piano by dissecting hers. Wow!! They play piano baseball, beat on drums, play memory, do theory with sidewalk chalk on the patio. It has all focused on "fun." My daughter's piano abilities have grown in just months with Miss P. Her theory on kids practicing on their own is that if they are enjoying piano, they will play. If they aren't playing, don't force it - they may need a break or to be introduced to a new piece of music.
Honestly, I don't have a real answer for your question, I'm just sharing what has worked for us.
It's wonderful that your daughter is learning piano at such a young age. Research links playing a musical instrument with receiving excellent grades. I'm sorry that you are having a hard time getting her to practice more. Children are mini adults who are attempting to grow and show their independence with every decision they make. She may really only want to play for the scheduled time and no more than that. You could try some reverse psychology and stop asking her to practice and maybe she may pick it up on her on volition. Sometimes pushing a child can backfire, so you're doing a really good job by thinking of constructive ways to encourage your daughter.
I hope this helps,
If you child requires more motivation, perhaps rewarding them with a small gift at the end of each week will be beneficial. Remember, your child will need a lot of motivation in order to focus on piano acquisition. Quality piano also will be a good motivation.