This applet uses two parallel number lines to represent pairs of numbers. The bottom number line shows the first number of a pair and can be moved on the line. The upper line shows the second number of the pair, . An arrow connects the two values.


The pair of values are related by an equation. Can you tell what the equation is by moving the x value? Selecting the Show Relation button will show the equation that relates the y value to the x value. Clicking the next button will use a different relation. Can you think of a better way to show pairs of values so that the relation between the values can be more easily seen?