Yes it can be one word.
one word
It can be one word and two words it just depends on how you are using it. As a noun it is one word. If "flow" acts as a verb (for example, "the work flows well"), use two words.
One workplace was created in 1925.
It is two words. Writing it as one is acceptable in the UK and is referred to as a "Britishism." But in American grammar, it is always two separate words.
it is two words
Two words - "one day".
"Pogostick" is typically written as one word.
two words
Complain to human resources
Complain to human resources
They are two words conjoined to be one.
I recommend class work, as two words.
It is two words.