Museum of Science, Boston

Paper Bridge Engineering at Different Ages

Books for Kids

  • Bridges Are to Cross
    , by
    Philemon Sturges
  • Bridges: Amazing Structures to Design, Build & Test
    , by
    Carol A. Johmann & Elizabeth Rieth
  • Engineering the ABC's: How Engineers Shape Our World
    , by
    Patty O'Brien Novak

Contact Us

Contact the Discovery Center and Living Lab staff at livinglab@mos.org

April 2012: Paper Bridge Engineering

Paper Bridge Engineering

In the Paper Bridge Engineering activity, children and their grownups practice their engineering design skills by building and testing their own paper bridge. Discovery Center visitors are encouraged to brainstorm about bridges, make a prototype, test it, re-evaluate, and re-design.

Engineers have many constraints when designing bridges, including the use of the bridge, the environment it is in, the materials that will be used, and the climate in which engineers are building. To help prepare, engineers may ask questions like:

• What will need to travel over or under the bridge?
• Will the bridge span a body of water?
• Will the bridge cut through a mountain?
• What resources are available? What materials are affordable?
• Does it rain a lot where the bridge will be built?
• Will earthquakes occur where the bridge will be buit?

The Paper Bridges activity introduces children to the science and math that engineers utilize when designing bridges for people or vehicles. During the activity, children are encouraged to think about geometry (what shapes are used to build real bridges), and challenged to apply what they know about shapes to their own paper bridge. Children are encouraged to set a goal for their bridge (e.g. building a bridge that will hold 20 plastic turtles, or some number of other objects). Children can also practice counting and carefully controlling variables as they design, test and re-design in order to reach their goal!

Paper Bridge Engineering at Home

You can continue your Paper Bridge explorations at home by:

Making a Paper Bridge at Home

Paper Bridge Materials List:

  • Side beams (two stacks of books, a small shoe box, or a narrow plastic tub)
  • Paper (cut the paper to a width slightly less than the width of your side beams)
  • Weights (pennies, poker chips or other "counters")
  • Rulers
  • Scissors (optional)
  • Balance Scale (optional)

    • Making a Paper Bridge:

    Set up a "valley" for your paper bridge to cross

    First, ensure that the two sides of the “valley” - whether it’s two stacks of books, a small box, a tub, etc. - that you create are even in height, and high enough so the bridge can have a little bend before “failing” (e.g., touching the ground, breaking, or falling off).

    If using multiple testing stations, make the stations consistent by using the ruler to measure a 6” space between the two sides of the “valleys” so that everyone has the same width to span with their bridge designs.

    Create a Prototype Bridge
    Use one piece of paper - place it across your "valley" as a bridge, and test it.
    • How much weight did it hold?

    Set a Goal, Test, Evaluate, and Redesign
    Using your one piece of paper, build a new bridge. Then, place it across your valley and test it.
    • How much weight did it hold this time?

    Questions to think about while experimenting:

  • How much weight can a sheet of paper hold?
  • How can you make a piece of paper stronger?
  • Where have you seen bridges before?
  • What are bridges used for?
  • What materials are bridges made out of?
  • Can you name three things an engineer does?

    • Considering Design Constraints for Bridges

    Engineers must consider

  • Usage: What will go over or under it? People walk, drive trains, drive cars, ride bikes, and ride horses as well as boat under bridges- the amount of material, shape, and length will be different if the bridge is just being used as a footbridge or used for large trucks to pass over.
  • Weather: Wind, sun, water, and earthquakes are all factors to think about.
  • Environment/Landscape/Climate/Weather: Where is the bridge being built? Going over water (river or ocean)? Going through a mountain? What type of soil is there? Does it rain a lot? Will earthquakes occur?
  • Materials available: What materials are available? What is affordable?
  • Budget: What can you afford?

    • Forces (or “stresses”) acting on bridges

    Too much of any of these can cause a bridge to fail:

  • Compression (a pushing force)
  • Tension (a pulling force)
  • Bridges can also be susceptible to bending, torsion (twisting), or shearing.

    • Bridge Types

  • Small divides: Beam or Arch
  • Large divides: Suspension

    • Bridge shape

  • Half circles are strong because when a load, or weight, is put on them, the entire shape is in compression. Bridges made of concrete often have arches because concrete is very strong in compression.
  • A triangle, the strongest of all shapes, is strong because when a load is added, the weight is distributed throughout the entire shape. Triangles are equally strong in compression and tension.

    • Find out about triangles in everyday objects!

    Materials and Budget Constraints

  • aluminum and steel are expensive, while wood and brick are very cheap.
  • concrete and cast iron are very strong in compression, but weak in tension.
  • reinforced concrete and steel are two materials very strong in tension and compression, but reinforced concrete can crack and steel can rust.