I don't think I've failed to understand common core, but you have misread my comment. How can you claim that I would support requiring a full sentence answer,

I don't think I've failed to understand common core, but you have misread my comment. How can you claim that I would support requiring a full sentence answer, when I already said "I always asserted that the answer is 6, not 6 miles, since the unit is given in the question."? I understand the common core requires full sentence answers (among other things) and I think this is wrong. I will repeat my reason. Math is not a different domain to ordinary reasoning, and word problems are not different to ordinary questions. So if "How many miles..." can be answered with "6" as a question in the English language (which it always can) then, "6" is a valid answer in the context of a math question. Requiring more, or accepting less (e.g. by accepting "6" as an answer to "How far..."), is obscuring the nature of math. Note this isn't an argument against showing work, but it is an argument that, in general, any valid reasoning should be accepted as showing work. The particular method should not be prescribed. But that is a less important point.