Translation:I need some sheets of paper to print a document.
I thought it was obvious from the context that the speaker was printing on bed sheets. I don't know how DuoLingo could have made it clearer, especially since the unit is called "In Class". It takes me back to my old school days when teachers would feed bed sheets into printers and then we would all have a nap.
It's nothing to do with avoir besion de. I find walking through this example the easiest way to remember:
I need the sheet of paper - j'ai besoin de la feuille de papier
I need the sheets of paper - j'ai besoin des feuilles de papier
I need a sheet of paper - j'ai besoin d'une feuille de papier
I need some sheets of paper - j'ai besoin de feuilles de papier
I wrote the same thing, but when I got it wrong I realized that they didn't choose 'papier'. 'Feuilles' means sheets, and just as we drop the 'sheets' from 'sheets of paper' which is more accurate, it seems they choose to drop the 'papier' from 'feuilles de papier' in French. Any native speakers who can confirm this?
Dear Duo: Please look at all the comments here. The word 'sheets' is NOT ubiquitously translatable with the word 'feuille' in either singular or plural. In the English language of any nation, US, Canada, Australia, NZ ect., typically the word "paper' must first be referenced either verbally or visually before saying "sheet" or "sheets" when speaking of paper. If I see some blank paper in the hands of someone or on a desk, ect, I could say "May I have a sheet?" But unless 'paper' is first somehow referenced, the responding person will always think the person is talking about bed linen. (There are other uses for 'sheet' such as the sails on sailing vessels, or in regards to what particular music a musician or composer would use)
MonsieurLeBleu. You are quite right in all your points, except one.
Allow me to inform you, "Sheets" are not sails on sailing vessels. "Sheets" are the ropes that control the sails of sailing vessels. They do the job of adjusting the angle of the sail to the wind.
I hope this helps