These are Misprint bins. We have 3 around our school to collect G.O.O.S paper in (Good On One Side). If you have paper in your classroom that you are not going to reuse (always your first option) and if it doesn't contain confidential information (full names, email addresses, assessment or personal information etc), then put it in the Misprint bin. This paper will be checked again (for good measure), then collected by Misprint, who turn it into very cool notebooks, which are sold for fundraising and in some shops.
We have 3 bins at our school this term: in the interview room (next to the office), in the photocopier/prep room (next to the staffroom) and in the G Block Atrium. Please use them!