Suspension Bridges, Part 2

For the second round of suspension bridges, I gave the kids more materials, and more explicit instructions on how to build it.  I wanted the kids to see just how much weight a suspension bridge can hold.  We create 2 towers from straws and taped them to the tables.  Then we placed a straw through the 2 towers to first create a beam bridge.  Those bridges were pretty stable, they held about 40-50 pennies.

Then we added string to the middle of the beam straw.  We pulled the string through the top of the towers and secured it to the table.  Now, the deck of our bridge was supported at each end by the tower and in the middle from the string.

Right away, we could see this was one strudy bridge.  We started weight testing.

I don't have any pictures of the weight testing, because each bridge held over 160 pennies (which was all the penny weight packs I had), we started adding dice.  We filled up each cup as much as it would hold, and the bridges were holding strong!  Not one of them even started to buckle.  It became obvious that we would need more containers to hold more weight.!!!

The kids were amazed at how much a straw bridge could actually hold without showing any signs of stress.  This is the perfect foundation of knowledge to have as we go on our bridge field trip and as we start to build our Portland bridges.