For those wondering "the child" appears to be a girl, based on pronoun slips in the original post. And this gifted girl was the same as her gifted girl, though I was a passive resister. I didn't fight, I just didn't do. And didn't care. And chocolate chips, $100, or a new car wasn't going to change me. I was bored with the method, with school, with everything. I did the bare minimum to get a B. that was it. I got straight As once, and my reward? "We'll, it's about time! Now let's see you keep that up!" I never repeated THAT mistake!
You have to change what you're doing. Radically. Worksheets, rows of problems she already gets, boring assignments or curricula? Get rid of them. She chose something to do with volcanos, no? Try that first. NOT the curricula (boring!), the subject. Use the curricula as reference material, but have her research elsewhere and come up with a presentation on volcanos. Tell her you'd like her to find out everything she can about volcanos in history, in science, in modern times. Pompeii, Mt. St. Helens, Hawaii, etc. say you want all sides, all perspectives. Then turn her loose.
And - she's 9. It's ok if she doesn't "keep up" with all her schooling right now. Once you get her going, she will more than catch up.