You can make the annual back-to-school supply-buying ritual a lot more challenging this year by visiting the well-stocked shelves of the Arlington Paper Supply Company, which has filled quite a few school, church and office supply cabinets over the past 25 years. The adventure begins when you attempt to decide what not to buy, for there are supplies to fill the work spaces of pre-schoolers, graduate students and everyone in between, not to mention business desks and homes. For the beginner, you'll find construction paper in three sizes and every color, plus childsafe scissors and paste, watercolors, crayons and fingerpaints. For older students there are aisles of notebooks, folders, composition books, loose-leaf paper, binders, typing supplies, pens and pencils and zippered plastic cases to hold them, and lunch boxes.You can also buy those bright foil stars that teachers affix to noteworthy school papers, and maybe give some special recognition to your own star pupils (or be creative and use them to decorate yourself or your surroundings). Everything on sale is an average of 15 percent below the suggested retail price. But the trick here is to buy as schools and offices do --the price another 10 percent in many cases. Besides, a gross of pencils can last you a long, long time.

Arlington Paper Supply Company, 3251 Washington Blvd., Arlington. Monday through Friday, 8:30 a.m. to 4:30 p.m.; Saturday, 9 a.m. to 3 p.m. 525-3211.