Use your straight edge ruler to draw a line segment two inches in length and label it length R. Label its endpoints A (left) and B (right). Extend the line segment half an inch past B and label the endpoint C.
Set the point of your compass at B and the pencil of your compass in between B and C. Draw a vertical arc. Without changing the degree of the compass, leave the point of the compass on B and place the pencil in between A and B. Draw an equidistant arc that intersects with the first arc. Align the straight edge at the two vertical points where the arcs intersect. Draw the two inch perpendicular to AB from these two points. Label the endpoint D.
Set the compass to length AB. With the point of the compass at A, draw an arc above A with the center at A. This arc will be called L. Set the point of the compass at D. Draw an arc that intersects with L and the center at D. Mark the point where the two arcs intersect. This point will be called E.
Use the straight edge to connect A to E and E to D. Draw both lines to complete the square.