The concept of visual guidance has also changed with the development of educational scientific methods, the expansion of visual guidance scope and the increase of projects. Local educational administrative organs pay more and more attention to assigning full-time and part-time visual guides to conduct specific inspections and guidance on various educational undertakings at all levels. For example, the heads of education administration in States, counties and school districts in the United States are not called directors or education directors, but inspectors, with assistant directors and inspectors. The main duty of education * * * is guidance, that is, going deep into the grassroots to conduct specific investigation and guidance.