Here's something that wokrs for us...The magical combination of Singapore Primary Math and the Key to series. This fall Catherine chugged through most of Singapore 5A learning the concepts behind operations with fractions. When we finished however it seemed that she wasn't recalling a lot of what she'd learned. We went back to Key to Fractions and now she's almost done the last book, consistently gets almost all the questions correct and can recall how to divide fractions or add mixed numbers at the drop of a hat. When we're through KtF I'll use the Singapore Intensive Practice for review and call fractions mastered.
It feels so damn good for both of us to have something so solidly learned.