Cartesian square

A cartesian square is a way to compare different pairs of things. It is like a grid - like a graph, but instead of having numbers on each of the lines, you have items or names. The top row has one set of items and the left column has another set of items. Where the rows and columns cross, you can write down how the items compare. For example, if the top row had different kinds of fruit, and the left column had different colors, in each spot you could write what color the fruit is.