I was just thinking...one thing that I use to track DS7's progress in math, is word problems. I find difficult, beyond grade level word problems (Singapore is my favorite right now), and hand them to DS to solve without my intervention.
It sounds simplistic, but it really gives me a lot of information about DS's thinking. Singapore is very analytical (I'm sure there are other great math curriculums). Some of the word problems, even at the fourth grade level (what we're working through) are challenging. It shows me that DS is able to complete about 70% quickly, without any instruction or input, but some of the multi-step, challenging problems require me to suggest strategies.
This may not be what you're looking for, but (at least in math), obtaining a math work book above grade level (something hard like Singapore or the AoPS) that emphasizes solving applied (not calculation) type problems will quickly reveal some strengths and weaknesses.
