# Invisible Forces  Mystery 2

In this Mystery, students will learn about bridge design and use their knowledge of forces to engineer a strong bridge made of paper.

## What makes bridges so strong?

Beginning Exploration (1 of 8)
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Beginning Exploration (2 of 8)

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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Beginning Exploration (3 of 8)

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

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Beginning Exploration (4 of 8)
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Beginning Exploration (5 of 8)

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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Beginning Exploration (6 of 8)
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Beginning Activity: Bridge Engineering!
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# Paper Bridge Engineering

Each student needs:

Each pair or group of students needs:

• ruler
• scissors
• several sheets of typing paper
• two stacks of books
• pennies (We recommend having at least 400 pennies on hand. Some bridges are VERY strong.)
• Bridge Challenge handout

The class will need lots of pennies for testing their bridges. We recommend you raid your penny jar or get several rolls of pennies from the bank.

The teacher needs a printout of Teacher Tips , which provides suggestions for guiding students when they are building bridges.

To prepare for the activity, we also 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.

Beginning Exploration (7 of 8)

##### 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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Beginning Exploration (8 of 8)
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Beginning Complete!

You've completed the Exploration & Activity!

If you have more time, view the assessment, reading and extension activity in the optional extras.

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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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# Golden Gate Bridge

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Beginning Activity: Bridge Engineering!
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# Paper Bridge Engineering

Each student needs:

Each pair or group of students needs:

• ruler
• scissors
• several sheets of typing paper
• two stacks of books
• pennies (We recommend having at least 400 pennies on hand. Some bridges are VERY strong.)
• Bridge Challenge handout

The class will need lots of pennies for testing their bridges. We recommend you raid your penny jar or get several rolls of pennies from the bank.

The teacher needs a printout of Teacher Tips , which provides suggestions for guiding students when they are building bridges.

To prepare for the activity, we also 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.

# 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
Exploration
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
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