From the lessons tips and notes: "Note that it is unnatural to say, for example, שתי שנים. You should always use the dual form, if one exists." Then shouldn't this be שבועיים ? I put "Both weeks" because of this and it was incorrect.
You are right that "שבועיים" sounds more natural, but they both mean the same thing.
"Both weeks" would be "שני השבועות"
I reported this as unnatural. Not because it's wrong, but because they wrote it in the tips & notes
I noticed a lot of people talk about those "Notes and tips". Where can I find them?
so this form of two is a dual ? Sorry I'm a little lost about ordinal and cardinal numbers