Students build bridges out of tape and cardstock and then test their designs to see how efficient they are. Efficiency is the mass supported by the bridge divided by the mass of the bridge. Your purchase includes:

• PDF file with structural template (U.S. letter size) for copying onto 65 lb. or 110 lb. cardstock
• Link to separate video instructions for teachers, students, and testing day
• Link to a Google spreadsheet for calculating efficiency of bridges, as well as formulas for assigning a curved grading scale based on efficiency (optional, of course).

You will need to supply the following items:

• two large buckets (such as 5 gallon buckets from Home Depot or Lowe's)
• ~25 pounds (11.3 kg) of sand
• a gram scale that can weigh bridges up to 250 grams
• a bathroom scale that can weigh over 25 pounds (11.3 kg)
• meter stick
• tape
• scissors
• Wooden testing block with hook - directions are provided for making this block
• metal chain - between 1 and 2 feet long (30-60 cm) - Ask someone at the store to cut a piece of chain at least a foot long, but no more than two feet long.
• s-hook - any size that can attach to the block's hook and the chain

This has always been one of my students' favorite projects every year.