Toothpick Bridge Time

I first wrote about toothpick bridges last November and recently repeated the activity with my high school students last week.  The goal of the Toothpick Bridge Project is to build a bridge made out of toothpicks and glue (wood).  The bridge is intended to be designed to hold as much weight as possible.  The only restrictions students and were:

1.  The bridge must cover a gap of at least 25 cm.

2.  The bridge must have a mass that does NOT exceed 50 grams.

Below are some high school student bridges from this year.

A 5 gallon bucket is hung from the bridge and slowly filled with sand.  In the past I've used water, which always makes a mess.  This year a student asked why I don't use sand as weight.  I thought about it for a second and thought to myself "why don't I use sand?!?!"  I even had a bucket of sand at home!  I brought it in and we slowly filled the bucket with sand until the bridge broke (had to use a few solid weights for the stronger bridges).  Not nearly the mess as I had with water.

Prior to this year, the record for most weight held was 73 pounds.  Bridges this year ranged from 3 - 89 pounds.  89 pounds!!!  Wow!  That's amazing!!!  And several bridges held between 60 - 80 pounds.  I was very impressed this year.

I haven't done this project with my daughters yet, simply because handling toothpicks and glue requires patience and skill they don't yet have.  When they are a few years older we'll do this project at home and see if we can top 89 pounds!