One of the greatest things I've learned throughout not only my own education, but also the education of the students that I have taught, is that you don't have to be extremely smart to excel in school. Of course it helps to be a genius but really anyone who really puts their mind to their work and puts forth the effort can do well in school. I find it's usually things like forgetfulness and lack of effort that cause grades to slip, and less about not understanding material. There definitely are students who don't understand a concept or struggle with a certain subject, but for the most part students who struggle in all subjects are forgetting to do homework, not taking notes during class, or simply not studying for tests and quizzes. A lot of it comes down to organizational skills. Many of these students just don't have the strategies to keep organized. A few simple things seem to really help children remember to do work:
1. Write it down! I've found that the biggest reason we forget to do something is because our brains are moving too fast and trying to remember too much that we can't remember everything. So we don't do our homework, and we don't bring our notes home or our book home to study. If we write these things down (in a planner, on a sticky note, even on our hand!) it will be easier to remember, and then the opportunity to earn a good grade doesn't just disappear.
2. 1 Binder, 1 Notebook, 1 Class! Stop mixing things up! Your notes should not be mixed in one notebook, they should not be loose in your backpack or tucked into random books, they should be in one place, with the other handouts from that class, so that you can study efficiently and not forget something in your locker or backpack.
I've found that these two things really help with most organizational problems. Of course, every child is different, but if we can teach our children organization skills, it will help them not only learn the subject they are studying, but help them learn more things in the future.