VISUAL DISPLAY EQUIPMENT-NAMELY, REMOVABLE AND NONREMOVABLE, INTERCHANGEABLE WRITING SURFACES MADE OF PAPER OR PLASTIC WITH PROTECTIVE COVER SHEETS THEREFOR FOR USE IN ASSOCIATION WITH CHARTS AND GRAPHS; WALL CHARTS AND GRAPHS; CHARACTERS, SYMBOLS, WRITING TABS, AND NUMERICAL INDICIA USED WITH WALL CHARTS; PORTABLE TRIPOD EASELS; MOVABLE STORAGE CONTAINERS FOR EASELS, PADS, AND CHARTS; TRANSPARENCIES FOR OVER-HEAD PROJECTORS; COMBINATION CHALK BOARDS AND EASELS; AND MAGNETIC WALL MOLDINGS FOR...