pointing finger animation

Bridge Out!
A Communication and
Skill Building Activity

by Eric Muller

Engineering and communication

Type of Web activity:
Sharing Information online

Materials / Software needed:
Web browser and/or email software.

Materials for construction (listed below).

Grade Level:
8 - 12

Time involved:
Several days

Created on:

November 2003

The Web Science Workshop lessons were created in cooperation with the Exploratorium Teacher Institute .


This site developed and maintained by Deborah Hunt and Eric Muller .

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San Francisco, CA 94123

© The Exploratorium

Your assignment:

A vehicle must be designed and built to carry a load across a 40-centimeter-wide chasm (Two tables separated by 40 centimeters). A bridge must be designed and built to support the vehicle. Both the design and building of the vehicle and bridge must be done as a team effort (four people per team). However, the bridge builders (two people) and the vehicle makers (two people) will be in separate groups and in separate locations. These two pairs will not meet until it is time to make the final crossing. All communication between these two groups must be conducted on the Web, in a Web chatroom (i.e. Yahoo chat ), through email or teleconferencing.

You may solve this problem any way you can as long as you follow the rules below. Grades and winners will be determined by design, originality, and weight ratio. The weight ratio will be determined by the weight of the load carried across the bridge / weight of the bridge + weight of the vehicle. This means, you want to construct the lightest vehicle and bridge possible that can carry a heavy load.

gap to be crossed

Here are the rules:

  • You must work in a team of four. This team will be divided into two pairs: the bridge builder group and the vehicle maker group.
  • Two of your team members must be in another location (another room, another period, another school, another state...).
  • The only acceptable manner of communication between pairs is through a chatroom , email or teleconferencing.
  • Groups cannot meet prior to the competition.
  • When the two groups meet, they will have only 5 minutes to set up the bridge and get the vehicle across the gap.
  • You may make as many crossings as you wish in 5 minutes, but only one of the crossings will count (the best run).
  • You may only use materials and supplies provided to you by the teacher.
  • Once the vehicle starts its journey across the bridge, it can not be touched until it reaches the other side of the bridge.
  • Vehicles must start 5 centimeters from the edge of the table.
  • The vehicle's starting elevation may not be higher than the vehicle's finishing elevation.
    You can't do this:

    you can't do this example

  • No part of the bridge structure may touch the floor.


Load to be carried by the vehicle: film canisters filled with sand.

The tables that will be used will be at least 1 meter wide by 2 meters long. The table tops will be 3 to 4 centimeters thick.

Both groups are limited to and will have access to the following materials:

  • blackboard (1/8" thick foam core)
  • straws
  • 1.5 volt electric motors
  • AA-size batteries (limit two per team)
  • string
  • rulers
  • protractors
  • plastic bottles
  • empty film canisters
  • newspaper
  • tape
  • white glue
  • hot melt glue
  • toothpicks
  • wire (thin gauge)
  • coat hangers
  • tools: scissors, pliers, hammer, etc
Good luck!


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