Add a Movable Point to a Graph
CODAP makes it possible to add a movable reference point to a graph. The graph must have numeric attributes on both axes.
To add a movable point to a graph, click on the ruler icon in the menu to the right of the graph, then select the check box for “Movable Point.”
A large yellow point will appear. If you click on the point, you can drag it around to wherever you want it to be on the graph. When you select the point, it will show a yellow box indicating the exact values of the variables on both the horizontal and vertical axes. As you drag the point around the graph, you will see the numbers in the yellow box change, to reflect the changing position of the point on the graph.