Patent US 7,052,279

A ten-frame subtraction system for teaching subtraction skills of the present invention preferably includes at least one card and at least one tile. The card has a positive numerical representation thereon represented by a corresponding quantity of graphical representations which are arranged in a predetermined arrangement. The tile has a negative numerical representation thereon represented by a corresponding quantity of cross-outs that are arranged in the predetermined arrangement. The tile is designed to interact with the card for teaching subtraction skills. Preferably the graphical representations remain visible through the tile if they are not covered by the cross-outs when the tile interacts with the card. The present invention is also directed to a method for using the ten-frame subtraction system to teach subtraction skills.