Color the solutions to systems of linear inequalities.

It can take a little while to sketch an accurate graph of the solution region of a system of linear inequalities with pencil and paper.  This GeoGebra Worksheet gives the user rapid feedback on whether or not an ordered pair satisfies one or both linear inequalities in a system.  As the point's color changes, the location of the solution region is revealed.  When the tracing feature is used, dragging the point around the screen actually shades the solution region in blue and shades the regions where only one or no inequalities are satisfied in either green or red. Finally, the boundary lines themselves can be toggled off so that for new systems, the solution region can be found in somewhat of a game of hide and seek.  Give it a try!