Patterns in graphs is the theme for April's IDEAS. Counting is the only skill prerequisite to learning to name points on a grid; all that's needed for each point is a pa ir of numbers. The French mathematician, Rene Descartes, invented the coordinate graphing system in the 17th century and provided a way to link geometric figures to algebra ic equations. Children at all levels can have some experience with this important idea of ma thematics, and graphing activities reinforce concepts of number.