Let's start by finding out a few things. Are you planning to use
Microsoft Word for this work? What Version? What exactly were the
directions? No more than 250 words per page? How many pages? Are there
divisions like chapters? Are header and footers counted in the 250 words?
Word can count the words, but I don't think there is any way it will
automatically put 250 on each page.
I am going to guess that you would prepare the entire work and then add
a page break as needed. Then send the result one page at a time.
Frankly this sounds screwy (like a Troll). Why would an instructor want
such a thing. I would think it would be a real bother for the instructor.