The truss bridge model in this activity has to be built using only wood dowels, craft-sticks, and carpenter’s glue. Some extra tools and materials like junior hacksaw, sandpaper, waxed paper, masking tape, wood, rulers, squares, drafting protractors, clamps, and paint for finishing, will be also used.

The dowels thickness, kind of wood, and quantity will depend on the truss assigned, its size, and required strength. Next is a generic list of materials, with approximate costs (In USD):

Use the following materials for bridges with a span of 20-28 inches:

• 1/4 in. x 36 in. square dowel ($1.00)
• 1/8 or 1/4 in. x 36 in. round ($0.90). Optional for truss elements. Trusses can be made with the ¼ square dowel; There are also bags of round dowels of different diameters, 12 inches long ($3.00)
• 5/16 in. x 4 ½ in. craft sticks ($3.00 bag w/100)
• 3/4 in. x 6 in. jumbo craft sticks ($6.00 box w/300)

Use the following materials for bridges with a span of 29-36 inches:

• 5/16 in. x 36 in. square dowel ($1.20)
• 1/4 in. x 36 in. round dowel ($0.50) Optional for truss elements. Trusses can be made also with square dowel
• 5/16 in. x 4 ½ in. craft sticks
• 15/16 in. x 8 in. extra or super jumbo craft sticks ($3.00 bag w/30)

Students may change the thickness dowels, or use only square dowels, depending on their designs.

Each group needs:

• wooden dowels and craft sticks (see amounts and sizes above), or have students purchase their own materials outside of class
• carpenter’s glue, such as Titebond II Premium wood glue
• junior hacksaw
• sandpaper, 100 and 220 grain found in a 3M general purpose packet)
• wax paper ($3.00 /roll)
• grid easel paper with a 1’’ x 1’’ grid, 2.5 ft x 2.08 ft
• meter stick or yard stick
• spring clamps or bar clamps
• drafting triangles, 30 cm – 12 in ruler, and protractor
• masking tape
• 40 x 12 cardboard sheets, two per group
• video recording device, such as a smartphone
• Project Overview and Activity Rubric

To share with the entire class on Day 4 (see notes in the Procedure for details):

• computer projector to display electronic format posters
• heavy objects, such as textbooks, to load models
• optional: a harness to load the bottom of the bridge