When I was 11, I quit piano to play football. I’ve been kicking myself ever since.
Now what about our kids? To prevent kids from quitting, you’ve got to lay a good groundwork of commitment.
First, you’re child has to be practicing consistently. Kids like things they are good at. And consistent practice will lead to improvement. If your child sees that he’s getting better, he’s more apt to stick with it. Even 10 minutes a day can propel a child’s piano playing forward and create a self-reinforcing habit.
Second, you need to expose your child to awesome piano players that he looks up to. What music does he listen to? Check out those bands and find out if there are any piano players. Then look up some videos of them on Youtube. It’s also helps if you take your kid to recitals by older kids in the neighborhood he may look up to. Anything that shows piano playing as something cool and neat will make him stick with it.
Third, your child has to respect and value his teacher’s views. Notice that I didn’t say “like.” That’s totally different. Kids are going to want to please people they respect. And if your teacher has your child’s respect and admiration, it’s going to make it much less likely he’ll quit.
Now, what if you haven’t laid that groundwork and your child just wants to quit piano? In this case, the question is how important is it to you. If it’s important, I’d consider a long-term bribe or reward. Something like if you keep with it for the next year, I’ll give you X. Generally, external rewards like this tend to be a bad idea. But if you match the reward with trying to lay down a groundwork of commitment (see above), then it may be worth it.