I personally have always struggled with school. Its not that I don't understand things, they just take me a longer time than they do for most other people. Also, I have ADHD so it makes it harder for me to sit down and actually get my homework DONE. I am in college now, but in high school gymnastics was like my rock. Even if school sucked, I would go to gymnastics and wouldn't have to think about anything but gymnastics for three whole hours. One time in high school I failed a class and my parents made me take a couple weeks off of gymnastics. This was the worst possible thing for them to do because I had all this extra energy that I couldn't get rid of and it made it even harder to focus. I eventually found out though, that I was most productive right after school and in the mornings before school. I tried to get most of my homework done after school and then do most of the rest at night. What I didn't get done at night, I would get up early to finish. I tried not to do this though because I didn't always know how long the rest of my homework would take.
Also, I know this is really hard to do, but try to make yourself do homework as soon as it is assigned even if it isn't not due the next day. Sometimes its nice to have a little break, but its even nicer when you know you have one less thing to do. The other thing is that its okay to have a snack break or something, but don't let yourself get distracted by other things. I know that if I let myself say 'oh I'm just going to watch TV while I have a snack and then when I am done eating, I will do my homework' the homework part happens way later than it should.
I don't know if it will, but I hope this helps!