You can use a legend to show a third attribute (variable) in a graph, in addition to the two attributes shown on the axes.
1. You need both the Table and Graph windows open.
2. Click and drag any variable name from the top of any column in the Table to the center of the Graph, as shown in the video.
3. When the graph region turns yellow, release the mouse.
4. The graph dynamically updates to show colored data points keyed to a color-coded legend that appears at the bottom of the Graph window. For numerical values, the darker the color, the higher the value of that legend attribute. If you place the cursor over (without clicking) a data point in the graph, it will now display three values for that point.