As a native speaker, this sounds correct:
There are a number of cows in that field.
whilst this sounds totally wrong:
There is a number of cows in the field.
But arguably the second form might be technically correct, because "a" indicates "a number" is singular.
Some examples support this hypothesis: "There is a collection of cows in that field."
Whilst others contradict it: "There are a lot of cows in that field."
Can you confirm which is correct, and is there a good justification which can be generalised to other situations?
