Might the school allow her to move to a classroom PC or lab during math for the purpose of participating in an online math program - which of course you would pay for. On any day the teacher is covering a topic that she needs reinforced, she could stay with the class but otherwise... Is 4th grade in the same bldg? Can she be subject matter advanced and join 4th for math. I know that is completely unheard of... we hit a wall here because the kids move bldgs every few years and they didn't want to transport her from one bldg to another. But some districts have (although I'd be suprised if you couldn't count them on toes and fingers).
You can offer to come in... but you might first want to ask what the school's policy is for dual enrollment (thanks to DYS for the term there). Because basically you are asking to partially homeschool without using the word. Because of our younger children we are going to lobby hard for something similiar in the fall... I have my hands in the air on the reading as nothing short of multiple grade skippings will help. And while we might need to make another one... well this is about you not me (fight narcissism now ;-)
