homeschooling

So all the homeschooling mom's out there, what's your recommendation for Math curriculum? I am teaching my niece, we just finished 4th grade and have been doing saxon math, she's had a hard time grasping some of the concepts and I'd love peoples input on different options out there. I know I'm not worrying about sat prep yet, but I'd still like her to understand 5th grade math. So what do you recommend? and while I'm asking for input, what about science too?