Can a child at any age add goodness to their faith, knowledge to their goodness, self-control to their knowledge, perserverence to their self-control, godliness to their perserverence, brotherly kindness to their godliness, love to their brotherly kindness?*
Is it progressive? Faith + goodness + knowledge + self-control + perserverence + godliness + perserverence + brotherly kindness + love. Or do we do it all, all the time. Can we do this no matter how old we are? Christian education is full of knowledge exercises. How about the others? What's godliness? What do these qualities look like? What do they sound like? What do they feel like?
We have sports, games, service. We probably correct bad behavior because we have to in order to manage a classroom.
Do we reward children (or adults for that matter) for choosing to believe God? choosing to be good? choosing to know what the Word says? choosing self-control? choosing to be kind? choosing to love? Even if no one's watching? Even if no one else is doing it? Even if it's not convenient? Even if it doesn't feel good? Even if "I don't want to?"
Do we pay attention and reward the small day-to-day choices that grow these character muscles?
"I noticed that you let your sister have the biggest cookie."
"I noticed that you got really angry but you walked away."
"I noticed that you helped Sarah with her project when you wanted to play."
"I noticed that you gave Lee a hug when he was sad and it made him happy."
"I noticed that you finished your homework instead of nagging me to watch TV."
*15-20 years ago, I used a character curricula, Jan Black's "Growing UP God's Way K-6" This is a revised curriculum. I really liked the songs and remember thinking it would have been even better with a group of kids. I used it homeschooling. I don't know much about the new version.