What makes bridges so strong?

What makes bridges so strong?

Lesson narration:
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Discuss: How could you keep a bridge like this from sagging? (On the next slide, we'll share one idea we had.)


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One idea we had: To keep the bridge from sagging, you could put a pillar underneath to support it.


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Discuss: Do the bridges you've seen so far give you any ideas about how you could make a strong paper bridge? (Think about how you can support the bridge so it doesn't sag.)

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Teacher Video - Guiding students to make bridges

The next slide is a video of Doug & Pat making different bridge designs. This is designed for the teacher to watch in advance. It will help you support students if they get stuck. (We don't recommend playing this video for the students before they've had a chance to experiment on their own.)

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Below are ideas for extending this topic beyond the activity & Exploration you just completed.
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Human Bridges

What would it feel like to be a tower on the Golden Gate Bridge? What forces would you feel as an arch bridge? To better understand the pushes and pulls at work in a bridge, your students can become the parts of different types of bridges.

  • Make a human suspension bridge with 16 students and two sturdy ropes in this activity from American Society for Engineering Education.

  • Create a human arch bridge in an activity from BUILDING BIG™, a five-part PBS television series.

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Paper Bridges

To learn more about paper bridges, check out these sites.
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Golden Gate Bridge

Learn more about this world-famous bridge.

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Image & Video Credits

Mystery Science respects the intellectual property rights of the owners of visual assets. We make every effort to use images and videos under appropriate licenses from the owner or by reaching out to the owner to get explicit permission. If you are the owner of a visual and believe we are using it without permission, please contact us—we will reply promptly and make things right.

Lesson Image
bridges by Jim Bowen , used under CC BY
Kirby Cove by Akos Kokai , used under CC BY
Charles Ellis by Mary Cone/PBS
Celestia software by Celestia , used under CC BY
Golden Gate from space by NASA , used under Public Domain
sleeping on boat by Jeff Mentzer
Golden Gate by James W. Shepp & Daniel B. Shepp , used under Public Domain
under the Golden Gate Bridge by USGS , used under Public Domain
USS Ronald Reagan transits Pearl Harbor by US NAVY Mass Communication Specialist 3rd Class Dylan McCord , used under CC BY
Shady Creek by Ladyheart
Kishwaukee River by IvoShandor , used under CC BY-SA
Bloukrans Bridge by http://niocem.ru/
Brunel's Suspension Bridge by Mark Gee
Lake Pontchartrain by Glenn
full hybrid truck by Walmart Corporate , used under CC BY
Seven Mile Bridge by kwalk628 , used under CC BY-ND
Lake Pontchartrain Causeway by Kari Csaba , used under CC BY-SA
Yanjinhe Arch Bridge by Glabb , used under CC BY-SA
NRG Bridge by Greg Mason Burns , used under CC BY-ND
Stone Bridge by cheriedurbin
Clifton Bridge by Adrian Pingstone , used under Public Domain
Golden Gate Bridge by Unsplash , used under Public Domain
spinning the main cables by Golden Gate Bridge District
hanging the roadway deck by Golden Gate Bridge District
GoldenGateBridge by Rich Niewiroski Jr. , used under CC BY
GoldenGateBridge at night by Ryan J Wilmot , used under CC BY-SA
steel construction by m.sansom
StafsWorcs Meccano Bridge by Sjwells53 , used under CC BY-SA
bridge number 6 by Mfwills , used under CC BY-SA
Healdsburg Memorial Bridge by Nate Botl , used under CC BY-SA
Phila Falls Bridge by Davidt8 , used under Public Domain
Carpenter's Flats Bridge by Mfwills , used under CC BY-SA
sewickley bridge by Robert Strovers
Golden Gate Bridge trusses by Jet Lowe , used under Public Domain
Lesson narration:

Activity Prep

Print Prep

In this lesson, students will learn about real-life bridge design. In the activity, Paper Bridge Engineering, students will use their knowledge of forces to build a strong bridge that supports as many pennies as possible -- using only paper.

Preview activity
COVID-19 Adaptations
Students can work solo
Digital worksheets available
See our advice below

Students at home
Students need the Bridge Challenge worksheet (printed or digital). Students can use pennies, paper clips, beans, rice or other items at home to serve as weights in the experiment.
Students at school
How to adjust the supply list so students can work solo: Each student needs the Bridge Challenge worksheet and 2x the number of books, sheets of paper and pennies as indicated in the supply list below.
Number of students:
Bridge Challenge worksheet 1 per pair
Bridge Designer’s Notebook worksheet 1 per student
Building Bridges Teacher Tips worksheet 1 per class
Blank Paper (8.5 x 11")
6 sheets per pair
Hardcover Books
6 books per pair
1 ruler per student
1 pair per student
We recommend having at least 400 pennies on hand for a classroom. Some bridges are VERY strong.
400 coins per class
Prep Instructions

We suggest students work in pairs. Homeschool students can work on their own.

Prepare With Some Engineering Inspiration

We recommend you watch this video of Doug & Pat from the Mystery Science team modeling how to build and improve a bridge. If your students get stuck, you can use this video for inspiration. Our Teacher Tips printout also provides suggestions for guiding students when they are building bridges.


22 mins

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