Hi Ania,
I agree with you 100%. My dd8 suplements her school work with problems from CML and mathcounts. Some of those problems are very challenging, but she actually enjoys doing them. This summer she will also be working on JHU Distance Education - Math Olympiad.
What they learn in their class is definitely not enough. She came home with her last test results last week. She received a 131% (she did all the extra credit problems). She was happy, I was not. She is +2 years in math and still not challenged at all. Next year she will be able to compete in CML and maybe even Mathcounts depending on her beginning of the year assessment. Until then, I just have to provide her with extra challenge at home.