LINK BODY, FOLDING STRUCTURE PROVIDED WITH SAME LINK BODY, AND SEPARATING MEMBER USED FOR SAME FOLDING STRUCTURE

Magnet sheet winding device and propping tool thereof

Flippable board method and system

Board describing or showing reality in four dimensions, a universal plotter and a scientific measurement and learning tool

Magnetic ring removably attachable to a pencil or eraser

Magnetic display including quick-release mechanism

BOARD DESCRIBING OR SHOWING REALITY IN FOUR DIMENSIONS, A UNIVERSAL PLOTTER AND A SCIENTIFIC MEASUREMENT AND LEARNING TOOL