I was just copyediting somebody's answer on another SE site and my native English speaker Sprachgefühl told me I had to correct the grammar of one sentence:
... 5–6 weeks are a lot of time ...
by changing the are to is. But as I was doing so I started wondering why is it that in this case it seems that I have to make the verb disagree with the plural subject?
So is my feeling for English going bad or if I did the right thing, how could I explain this to somebody who's learning English for instance?