Math Is a Series of Building Blocks
I find that many students have a fear of math. One reason for this fear is that math continues to builds on itself. For example, if you have difficulty w Algebra 1, chances are unless you go back and relearn it, you will continue to struggle w Algebra 2, pre calc, etc. I realized this as I would start tutoring a student in more advanced classes, but they never understood the PEMDAS concept from Elementary school.
Most schools nowadays, tend to push the kids through to higher in order to raise their ratings. My feeling is that if a child is struggling in Algebra 1 as an 8th grader, they should consider retaking the course in 9th grade. It will give them a confidence boost in math and help their GPA too. If you push them ahead, it could turn out much worse later on. Since you need a solid foundation to build a skyscraper, you should not advance in math until you understand the basic concepts. Go back and relearn them and you will move forward w understanding and will benefit down the road.