Draw 30 parallel lines across a cardstock sheet with a pencil and metal ruler. The lines should run perpendicular to the 14-inch side of the cardstock.
Use a razor blade to cut along each line. Place the metal ruler beside each marked line to make straight cuts.
Use bridge chord, strut, post and beam templates available at http://bridgecontest.usma.edu/pdfs/la1.pdf to trace on cardstock and cut out. Fold the tubes according to the fold lines and secure with rubber cement.
Research various truss structures, such as lattice and bowstring, and choose one to create for your bridge.
Measure and draw gusset plates and diagonal templates in accordance with your chosen truss structure. Trace and cut out the gussets and diagonals.
Consult bridge diagrams and pictures to assemble top and bottom chords, verticals, diagonals, bracing, struts and floor beams of your bridge and hold together with straight pins. Secure with wood glue.
Test the structural support of your bridge by adding textbooks on top of the trusses one at a time. Place each book on a scale prior to placing it on the bridge to calculate the total load your bridge will support without structural damage.
Perform calculations in class to compare the height, angles and number of triangles in the truss of each structure. Determine as a class which combination supports the greatest load, and which is best over long distances.