Maybe it depends a bit on what exactly you mean by focus? I think your second thought, that it would be sad to deprive your son of the science he loves, is absolutely correct. OTOH, you have only a finite amount of time and energy to put into choosing material and supporting his learning - it might make sense for you to put more of *your* time and energy into his weaker areas, since those are where he may need the support more, even if he's spending the same amount of time on each subject area.
Welcome, too! I think you'll find this a useful place to be. My DS-just-6 is also very keen on science; he's in school and it's going well so far, but I do realise how lucky we are in having a school available that meets his needs.
