If a school building has square glass windows that are not see-through, it means that the windows are not transparent and one cannot see through them. This could be for a variety of reasons, such as for privacy or security, to control the amount of light entering the building, or to prevent glare or heat gain, and you can also click for info today. You must here about frosted or etched glass, as this type of glass has a frosted or etched surface that diffuses light and makes it difficult to see through.