I would keep it brief-- experiencing success in as small a window of time that is practical. For example, have her complete 2 short or 1 long math problem. Then let her go bounce around or switch to the subject of her choice, one she is more focussed on. Do this until she can complete this small chunk easily, then add to it if you'd like her to focus for longer (though you might not have to. And give her fair warning.)
My girls, though not particularly bouncy, have definite bouncy times of day. As a homeschooler you can take advantage of any (slighty?) calmer moments. Create those moments by heading to the park or going for a bike ride, then home for lunch and some (calmer?) focus time. Very brief, of course!
A bit of advice aside from homeschooling, be sure not to make her bounciness into an issue that makes her feel bad about being the way she is. (I'm thinking of the Pooh "Chapter 7 In Which Tigger is Unbounced"!)
Also introducing conscious focusing techniques might not be a bad idea. Yoga, meditation. Our Wilderness Awareness for Kids books advocate a "sit spot" or "secret spot" in the yard that encourages silent observation.
All, of course, in very small chunks of time!