Whether you do so on a voluntary basis (i.e. 2-3 hours a week with your local library's homework help) or privately (by posting ads) or professionally (through one of the tutoring services) please consider tutoring. Talented math teachers can truly turn tides.
I was a GATE kid, but I had serious difficulties with mathematics in 3rd through 5th grade. Some was performance anxiety (I could not handle timed speed tests -- I froze) and some was a difficulty with some concepts. (My grandmother taught me the decimal equivalents for most fractions when I was very young but not how to convert back, so I was doing all of my fractions math as decimals... which wasn't the point.) I almost blew a year of school because of this, but a talented, retired math teacher tutored me. I got caught again in high school -- geometry made absolutely no sense to me until another tutor figured out that applying algebra to geometry was my personal key. (I do much better with abstraction.) Thanks to those two women, I learned to love mathematics, so much so that I'm now a statistician. Without them, I probably would have blown out on most higher mathematics, and thus blown my chances for a career.
I am not unique -- a lot of girls don't get effective mathematical tutoring because we don't have the language skills at the time to articulate our difficulties. Further, our parents or guardians may not remember or understand what difficulties we're having.
I am not a fan of the various education privatization schemes (like tutoring companies and charter schools) but I also realize that fixing the mess in public education is going to take a federal, state and local response, and the children who are struggling now don't have time to wait for we adults. Your tuition of a struggling student will certainly help that student, and may alleviate some of the pressure on the teachers still in the classroom -- which gives them the time and energy to fight their administrations and be better advocates. Tutoring has advantages (No administration, involved and concerned parents, motivated students, plus a flexible schedule and a small class).