Toothpick Bridges

A great activity that you can do with kids of all ages is the toothpick bridge building and breaking.  This is a required project in my high school physics classes, but it's something that you can do with kids of any age.  For a summer camp a couple of years ago I had 3rd, 4th, and 5th grades build toothpick bridges.  If you have younger children you can replace the toothpicks with popsicle sticks.  The goal is to build a bridge that is strong, sturdy, and can hold a great amount of weight.  My high school students have the following restrictions:

1.  You may only use toothpicks and glue (wood glue is fine).

2.  The bridge must span a gap of at least 25 cm.

3.  The bridge must have a mass of no more than 50 grams (in other words, an unlimited number of toothpicks is not allowed).

After the bridges were constructed, students brought them to lab and we tested how much weight each bridge could hold.  A 5 gallon bucket was place on the bridge and the bucket was slowly filled with water until the bridge broke.  Below are a few designs students came up with in my class.

The last picture shows the bucket being supported by the bridge.  This year I was very impressed with my students' bridges.  Last year the best bridge held 40 - 45 pounds of water.  This year one bridge held 50 pounds which was fantastic, but it was outdone by another bridge that held 73 pounds, which is doubly fantastic!!!  I had a great video of the 73 pound bridge break, but unfortunately the file size is much to large to upload here.  You'll just have to use your imagination.  

The bridge break is a great activity that gets students to think outside the box.  It can be done with any age group.  You can stick with the restrictions I used, or make up your own.  The younger the student, the more help they will need, but this is a great way for you to bond with your child.