I would suggest asking your school for the scope and sequence, or depending on your state for the GLCE's. With it being a private school things can vary, a lot. They should have to provide it without question. Just be prepared that they are broad statements that are hard to actually measure and as mentioned earlier, most are repetitive from one year to the next. I think it is most beneficial, if you plan on keeping him in private or even public school, to advocate for science when it becomes and issue with math, as already mentioned. Until then you aren't going to get much variation.
My DD sat down last year and decided she wanted to complete fourth, fifth and sixth grade science, it really wasn't that hard. This year her plan is to finish up middle school science so she can move on to "real" science next year. When you start looking at Algebra 1 then it makes sense to look at science.
History, I doubt that unless he is a history buff that advocating there is worthwhile. Otherwise you are back to whole grade acceleration to address math, science, and social studies.
