Subject/Strand/Topic:
Science / Structural Strength and Stability
Grade
7
Key Concepts: bridges, structures, strength, stability, forces
Ontario Expectations:
7s84, 7s85, 7s86, 7s87
Link: http://www.pbs.org/wgbh/buildingbig/bridge/challenge/index.html
Required Materials: † Pre-Assessment/Answer Key, † Teacher-Led Handout, † Teacher-Led Handout Answer
Key, † Post-Assessment/Answer Key † Data Projector
Before Starting:
1. Students should have a general understanding of characteristics of structures, strength and stability.
2. Practice using, and be familiar with the learning object prior to lesson.
Introduction (~ 5-10 minutes including pre-assessment)
2. Teacher-led discussion: Ask students to describe the different types of bridges they have seen. Q: Why do we have so many different types of bridges? (Different bridges are good for different situations, some for distance, some strength, etc.)
3. Introduce learning object to class.
Use of Learning Object with Handout (~ 30 minutes)
1. Distribute handout; explain organization.
2. Use learning object to guide students through questions in handout. Prompt students when to fill in information.
3. Part 1: Bridge Basics (scroll to bottom of first page, under the bridge locations, click “Bridge Basics”) a. Go through the 4 types of bridges. Click on the picture of bridge. b. While picture is showing, ask students about characteristics of bridge, advantages, disadvantages, forces acting on bridge, etc. When done, click “Back to bridge basics” c. From “Bridge Basics” screen, click on button “Forces” to explore forces acting on the bridge. d. Verbally summarize information about bridge. Prompt students when to fill out question 1 of handout. e. Repeat for remaining bridges.
4. Part 2: Bridge Challenge (click “Bridge challenge” at bottom of “Bridge Basics” screen) a. Explain goal of bridge challenge. b. For each location (do location 1 last): i. Have a student read aloud information about location. ii. Have students guess what type of bridge they should use e.g. individually, by show of hands, class poll, etc. (have students record guess in question 2) iii. Go through some of the wrong answers first and THEN correct answer. Have students contribute their ideas why it is good/bad solution, then, summarize why each is wrong/right. iv. Prompt students when to fill out question 2 of handout. c. Give students 2 minutes to answer question 3. Discuss answer when done.
Tips and Tricks
ƒ Don’t read directly off screen. Tell students important information and focus on pictures/ diagrams.
ƒ Bridge challenge:
- Locations have multiple parts and provide good opportunities for reasoning and decision making.
- Try to involve students whenever possible (predicting, reading info off screen, etc.)
Consolidation (~ 5-10 minutes including post-assessment)
1. When learning object/handout complete, distribute the Post-Assessment; collect (5 minutes).
2. Ask follow up questions, e.g., Q: When would you use a suspension bridge (long span, over water) Q: When would you use a beam bridge? (short span, cheap, no need for boats to pass).
3. Collect handout as ticket-out-the-door
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Plan
Page 1 of 1

The Bridge Challenge
Teacher-Led Lesson Pre-Assessment
___________________________
Birthday : ____________________________
5
1. List 3 (three) types of bridges that are commonly built? [3 marks]
2. Imagine you have to design a bridge that pedestrians, bikers and rollerbladers can use, that is cheap to build and can withstand the occasional flash flood. What type of bridge would you build? Explain your answer. [2 marks]
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Pre-Assessment

The Bridge Challenge
Teacher-Led Lesson Pre-Assessment Birthday : ____________________________
5
Answer Key
1. List 3 (three) types of bridges that are commonly built? [3 marks]
Arch, beam, suspension, truss
2. Imagine you have to design a bridge that pedestrians, bikers and rollerbladers can use, that is cheap to build and can withstand the occasional flash flood. What type of bridge would you build? Explain your answer. [2 marks]
Beam bridge with deep piers: cheap, easy to build, can span the distance well. Deep piers will help prevent the bridge from moving during a flood.
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Pre-Assessment

The Bridge Challenge
Teacher-Led Lesson Handout Date: _____________________________
PART 1: Bridge Basics [8 marks]
1. Complete the chart as your teacher goes through the learning object. [8 marks]
20
Type of bridge
Truss
Arch
Beam
Suspension
Important features Forces acting on bridge
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Handout
Page 1 of 2

The Bridge Challenge
Teacher-Led Lesson Handout Date: _____________________________
Your Task:
•
Figure out which type bridge is right for each location.
•
You will need to consider the characteristics of each bridge, the location, and what the mayor and town wants too!
2. Complete the chart as your teacher goes through the learning object. [8 marks]
Location Bridge type
(take a guess)
Correct bridge type
Reason for choice
1
2
3
4
Multilane bridge for commuters and tourists
Span : 2,000 feet
Crossing : River
Connects : City and major highway
Footbridge across a stream
Span : 100 feet
Crossing : Stream
Connects : Two bike paths
Highway bridge across a busy shipping port
Span : 5,000 feet
Crossing : Ocean bay
Connects : Island and mainland
Railroad bridge in a national park
Span : 500 feet
Crossing : Deep river gorge
Connects : Two rocky bluffs
3. List 4 (four) factors you need to take into consideration when building a bridge? [4 marks]
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Handout
Page 2 of 2

The Bridge Challenge
Teacher-Led Lesson Handout Answer Key
Name: Teacher Answer Key
20
1. Complete the chart as your teacher goes through the learning object. [8 marks]
Suggested answers given. Answers will vary with the detail you want your students to have.
Forces acting on bridge Type of bridge
Arch
Beam
Truss
Suspension
Important features
- Horizontal beam supported at each end by piers .
- Bridge is weaker the farther apart the peirs.
- bridges rarely span more than 250 feet.
- made of many triangles.
- made from straight, steel bars.
- Cantilever bridges are an example.
- bars rarely bend – can span large distances
- has great natural strength.
- most arch bridges are made of steel or concrete ,
- can span up to 800 feet.
- can span 2,000 to 7,000 feet (farther than any other type of bridge)
- roadway hangs from massive steel cables , draped over two towers and secured into solid concrete blocks
- towers support weight
- When something pushes down on the beam , the beam bends .
- every bar has a pushing or pulling force
- arch is squeezed together
- supports, push back on arch and prevent ends of arch from spreading apart.
- have a truss system underneath roadway to resist bending and twisting.
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Handout Answer Key
Page 1 of 2

The Bridge Challenge
Teacher-Led Lesson Handout Answer Key
Name: Teacher Answer Key
2. Complete the chart as your teacher goes through the learning object. [8 marks]
Location
Suggested answers are given. 2 marks per row. No marks given for guessing the type of bridge.
Bridge type
(take a guess)
Correct bridge type
Reason for choice
1
2
Multilane bridge for commuters and tourists
Span : 2,000 feet
Crossing : River
Connects : City and major highway
Footbridge across a stream
Span : 100 feet
Drawbridge / then
Cable-stayed bridge
Beam bridge with deep piers
- drawbridge can span the distance and let boats through.
- cable-stayed bridge, similar to suspension, no steel, can do a long span
- beam bridges, cheap, easy to build, covers appropriate distance. The deep piers prevent the bridge from failing during a flood
3
Crossing : Stream
Connects : Two bike paths
Highway bridge across a busy shipping port
Span : 5,000 feet
Crossing : Ocean bay
Connects : Island and mainland
Suspension bridge with open truss
- suspension bridge, spans large distance, can let ships pass. The open truss lets wind pass through but stiffens the deck
4
Railroad bridge in a national park
Span : 500 feet
Crossing : Deep river gorge
Connects : Two rocky bluffs
Arch bridge with steel
- rocky edges support abutments of bridge, no piers needed
- steel is strong in compression and will last
3. What factors do you need to take into consideration when building a bridge? [4 marks]
Span, use of bridge, strengths/weakness of each bridge type, what the public wants, cost of bridge, length of time
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Handout Answer Key
Page 2 of 2

The Bridge Challenge
Name: ___________________________
Teacher-Led Lesson Post-Assessment Birthday : ____________________________
5
1. Imagine you have to design a bridge that pedestrians, bikers and rollerbladers can use, that is cheap to build and can withstand the occasional flash flood. What type of bridge would you build? Explain your answer. [2 marks]
2. List 3 (three) types of bridges that are commonly built? [3 marks]
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Post-Assessment

The Bridge Challenge
Name: ___________________________
Teacher-Led Lesson Post-Assessment Birthday : ____________________________
5
Answer Key
1. Imagine you have to design a bridge that pedestrians, bikers and rollerbladers can use, that is cheap to build and can withstand the occasional flash flood. What type of bridge would you build? Explain your answer. [2 marks]
Beam bridge with deep piers: cheap, easy to build, can span the distance well. Deep piers will help prevent the bridge from moving during a flood.
2. What are 3 types of bridges that are commonly built? [3 marks]
Arch, beam, suspension, truss
© 2007 University of Ontario Institute of Technology (UOIT) ~ Permission to Copy
Teacher-Created Resources: Teacher-Led Lesson Post-Assessment