Bridge Builder

This activity allows students to try their hand at designing bridges. The activity uses Bridge Builder, an AgentSheets project designed by Alexander Repenning that can be run as a Java applet within your internet browser or can be run as a stand alone project on your computer if you download and install a version of AgentSheets.

Goal / Objective
The goal of Bridge Builder is to make the most efficient bridge, defined as the bridge with the fewest bricks.

Using the simulation
The bricks tell you how much stress or tension they have on them by turning shades of red. The more tension, the more red they are. If there is too much tension on a brick, it will fall out the bridge.

Press the Run button. You will see the cars traveling across the bridge.

To remove bricks:
 * Click on the eraser tool.
 * Now click on a brick to remove it from the bridge.

As you remove bricks, some of the remaining bricks may turn pink or red, showing the amount of tension on the bridge. Some tension is okay and necessary to build an efficient bridge. Too much tension will cause the bridge to collapse.

If the bridge collapses and the cars begin to crash:
 * Press the Reset button.
 * Press the Run button.
 * Repair your old design or try a new one.

To add bricks:
 * Click on the brick icon in the Gallery
 * Click on the pencil tool in the Worksheet.
 * Now click on the worksheet to add bricks.

Remember that to build the most efficient bridge, you will probably have some bricks that are showing red. That is okay, as long as they don't fall out.

Questions to Answer

 * In the original picture, how many bricks are in the original bridge?
 * The top row of bricks is required to make the road. How many supporting bricks are below the top layer?
 * Build a bridge. Sketch a picture of your bridge. How many supporting bricks (not counting the ones in the road) did you use? What fraction of the supporting bricks were you able to remove?
 * Build another bridge that tries to use fewer bricks. You may need to use the pencil tool, to add some bricks before you take other bricks out. Sketch a picture of your bridge. How manysupporting bricks did you use? What supporting bricks did you use? What fraction of the supporting bricks were you able to remove?

Teaching Material

 * [[Media:StudentActivity.pdf | Student Activity (pdf)]]: Original PBS Activity handout for students
 * [[Media:Answers.pdf | Answers (pdf)]]: Answers to the original PBS Activity handout for students

Resources
AgentSheets
 * AgentSheets: AgentSheets Inc. web site.
 * AgentSheets Projects Showcase: example projects built with AgentSheets.
 * AgentSheets Download: trial download for the AgentSheets software.

Bridges
 * The Bridges of LEGO®:

Math Challenges
 * The Golden Section in Art, Architecture and Music.
 * The Yurt: A page devoted to the construction of a Yurt.
 * The Mongolian Felt Tent.