A training system of visual aid, particularly for reproducing and studying configurations and problems varied geometry in three dimensions comprises a sphere (11) on the surface of which can draw or write and is made of a transparent or translucent material or another material of the same type. Said system also comprises a support (2) for holding the sphere in place, and a spherical ruler, adapted to the surface of the sphere in any position. The spherical rule consists of a ring (3), a shelf (4) perpendicular to said ring (3) and one or more handles (5). The support (2) forms a torus under the ball (1) to firmly hold said sphere (1) in any position on the core (2). The edges of the ring indicator (3) and the shelf (4) lie on arcs of larger circles. A joint, perpendicular to the ring (3) and the shelf (4) is inserted between said ring (3) and said shelf (4), said seal also being adapted to the surface of the sphere (1). The lower side of the joint (6) has two contact ends (10, 11) separated by an appropriate space. The outside of the seal (6) is provided with a rounded nose elongate (7) serving as a support. One side of the shelf (4), preferably adjacent to the seal (6) is provided with a solid, thin plate (5) serving as a handle, the top of said plate (5) having two rounded ends (5A, 5B).
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