Abstract: Different types of measuring devices detachably built up with different elements are provided. The elements for forming the built-up measuring devices include suitable numbers of connecting rule elements, corner elements, swing elements, fixing bars, and fixing sleeves. The measuring devices that may be built up with the elements include but not limit to ruler, square, three-dimensional square, and arithmetic balance. These measuring devices integrate functions of many commercially available intellectual aids and can be used to take linear, area and cubic measures, practice four fundamental operations, and learn concepts about coordinates.