An educational ball having a body being a square block and having six outer surfaces connected to each other to form the body; six mounting recesses respectively formed in the outer surfaces of the body, and each one of the mounting recesses having a center; and six engaging holes respectively formed through the centers of the mounting recesses; and multiple operating sets connected to the body, respectively and rotatably mounted in the mounting recesses, and each one of the operating sets having a rotating mount rotatably mounted in a corresponding mounting recess of the body, and having an inner side; an outer side; an outer periphery; an engaging jacket formed on and protruding from the inner side of the rotating mount, extending in one of the outer surfaces of the body, and engaging one of the engaging holes; and multiple sliding sheets movably mounted on and covering the rotating mount, and characterized in that the rotating mount of each one of the operating sets has two inserting holes formed through the outer side of the rotating mount beside the engaging jacket; and each one of the operating sets has two covering plates connected to the rotating mount at an interval to cover the outer side of the rotating mount, and each one of the covering plates having an inner surface covering a part of the outer side of the rotating mount; a flat inner edge facing the flat inner edge of the other covering plate at an interval; a curved outer edge; an outer side; a connecting pipe formed on and protruding from the inner surface of the covering plate, extending in the outer side of the rotating mount, and engaging one of the inserting holes to hold the covering plate with the rotating mount; multiple track grooves formed through the curved outer edge of the covering plate and spaced apart from each other at intervals; and a guiding channel formed in the flat inner edge of the covering plate; and a sliding groove formed between the guiding channels of the covering plates, aligning with the track grooves of adjacent operating sets, and communicating with the sliding grooves of two of the operating sets; the sliding sheets of each one of the operating sets are movably mounted in the track grooves of the covering plates and the sliding groove of the operating set to cover the rotating mount, and each one of the sliding sheets being curved and having an outer surface exposed from one of the track grooves or the sliding groove of the operating set; and a mark formed on the outer surface of the sliding sheet; amount of the sliding sheets of one of the operating sets is fewer than amount of the other operating sets to form a gap on a corresponding operating set. six outer surfaces connected to each other to form the body; six mounting recesses respectively formed in the outer surfaces of the body, and each one of the mounting recesses having a center; and six engaging holes respectively formed through the centers of the mounting recesses; and a rotating mount rotatably mounted in a corresponding mounting recess of the body, and having an inner side; an outer side; an outer periphery; an engaging jacket formed on and protruding from the inner side of the rotating mount, extending in one of the outer surfaces of the body, and engaging one of the engaging holes; and an inner side; an outer side; an outer periphery; an engaging jacket formed on and protruding from the inner side of the rotating mount, extending in one of the outer surfaces of the body, and engaging one of the engaging holes; and multiple sliding sheets movably mounted on and covering the rotating mount, and characterized in that two covering plates connected to the rotating mount at an interval to cover the outer side of the rotating mount, and each one of the covering plates having an inner surface covering a part of the outer side of the rotating mount; a flat inner edge facing the flat inner edge of the other covering plate at an interval; a curved outer edge; an outer side; a connecting pipe formed on and protruding from the inner surface of the covering plate, extending in the outer side of the rotating mount, and engaging one of the inserting holes to hold the covering plate with the rotating mount; multiple track grooves formed through the curved outer edge of the covering plate and spaced apart from each other at intervals; and a guiding channel formed in the flat inner edge of the covering plate; and an inner surface covering a part of the outer side of the rotating mount; a flat inner edge facing the flat inner edge of the other covering plate at an interval; a curved outer edge; an outer side; a connecting pipe formed on and protruding from the inner surface of the covering plate, extending in the outer side of the rotating mount, and engaging one of the inserting holes to hold the covering plate with the rotating mount; multiple track grooves formed through the curved outer edge of the covering plate and spaced apart from each other at intervals; and a guiding channel formed in the flat inner edge of the covering plate; and a sliding groove formed between the guiding channels of the covering plates, aligning with the track grooves of adjacent operating sets, and communicating with the sliding grooves of two of the operating sets; an outer surface exposed from one of the track grooves or the sliding groove of the operating set; and a mark formed on the outer surface of the sliding sheet;