Building a Bridge
1. Title of the Lesson: Building a Bridge
2. NJ Core Curriculum Content Standards addressed in the lesson.
 5.1.12.B.1 (Logically designed investigations are needed in order to generate the
evidence required to build and refine models and explanations): Design investigations,
collect evidence, analyze data, and evaluate evidence to determine measures of central
tendencies, causal/correlational relationships, and anomalous data.
 5.1.12.B.3 (Empirical evidence is used to construct and defend arguments): Revise
predictions and explanations using evidence, and connect explanations/arguments to
established scientific knowledge, models, and theories.
 5.1.12.D.1 (Science involves practicing productive social interactions with peers, such as
partner talk, whole-group discussions, and small-group work): Engage in multiple forms
of discussion in order to process, make sense of, and learn from others' ideas,
observations, and experiences.
 5.1.12.D.2 (Science involves using language, both oral and written, as a tool for making
thinking public): Represent ideas using literal representations, such as graphs, tables,
journals, concept maps, and diagrams.
 5.2.E (Forces and Motion): It takes energy to change the motion of objects. The energy
change is understood in terms of forces.
3. Identify Resources needed. (identify texts, equipment, media, family or community resources
to be used in the lesson).
a. Teacher Use: Ruler, Tables or desks, pennies or other objects for bridge strength testing,
container to hold pennies with clips to attach to bridge prototypes
b. Student Use: Toothpicks, gumdrops, scissors
4. Describe what students should know before they start the lesson.
 Students should be able to work cooperatively in small groups. They should listen to and
have respect for others' ideas.
 Students should understand the steps involved in the engineering design process.
 Students should be able to draw force diagrams and to apply that skill to the bridge
building task.
5. State the objectives of the lesson.
 Students will increase their ability to work cooperatively to solve a problem.
 Students will learn how to use a systematic approach to solving a problem.
 Students will learn about torque and how it relates to bridge design.
 Students will learn how to use the engineering design process to solve a problem.
 Students will learn that engineering involves using their ideas and knowledge to solve
real-world problems.
 Students will learn about how to balance the cost of materials with the benefits they
provide.
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Students will learn about civil engineering (building structures such as bridges), but also
that other engineers are responsible for developing stronger, cheaper, or more
environmentally friendly construction materials. Students will learn how the work done
by engineers affects society for the better.
Students will apply their knowledge of physics to solve a real world problem.
6. Identify important ideas in terms the subject area - describe in detail. Real life connections
(make a list).
 The engineering problem-solving strategy (which mimics the ISLE cycle for
experimentation) involves devising a series of possibilities that are tested and revised.
 The eight steps of the engineering design process are: identify the need or problem,
research the need or problem, develop possible solutions, select the best possible
solution, draw a prototype, test & evaluate, communicate the solution, and redesign.
 The engineering design process includes constructing a physical prototype: starting with
plans and ideas, using materials to build the physical model. This prototype can then be
tested, and the results applied to redesign and improve.
 Torque: Sum of (force * radius from pivot point). For a structure to be stable, not only
must the sum of the forces exerted on it be zero, but the sum of the torques exerted on it
must also be zero. When the building materials (gumdrops & toothpicks) can no longer
provide a sufficient force and torque to counter those exerted on the bridge by the
hanging penny container, the bridge will begin to break apart.
7. Describe potential difficulties students may experience with the content. Describe all
formative assessments that you plan to use and how you will provide feedback.
 Students may have difficulty working cooperatively. One group member may dominate,
especially boys in mixed gender groups.
 Students may have difficulty applying the engineering design process, rather than just
employing a trial and error strategy. I will remind the students to plan ahead. Also, I can
present the problem but not make the materials available for the first five minutes, which
will force students to plan (steps 2-5) before building their prototype.
 I will monitor the groups, and make sure to engage group members whose opinions don't
appear to be being listened to. This will demonstrate to the dominating group members
that the others' ideas are to be valued. This also will ensure that all group members are
contributing equally, and that all group members understand the successes and failures of
their prototypes.
 I will ask groups what problems they are having, or what is standing in the way of their
meeting their goals, to engage them in a discussion about the possible strategies they
could employ to solve their problems, rather than just using trial and error. Students may
need to be prompted to systematically change one aspect of their design at a time to solve
the problem. I will ask students what assumptions they made in their initial plan that
turned out to not be valid, and how they have revised their assumptions.
 If a group adopts a new approach, I will ask them to explain what they changed and the
reason for the change. In addition, I will try to get them thinking about the physics
explanation for the failure of their prior prototype.
8. Provide a description of the lesson including an agenda for the lesson.
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
See handout attached at end of lesson plan
9. Time Table – who is going to be doing what and when during the lesson to make sure that
students are actively engaged.
Clock reading
“Title of the
Students doing
Me doing
during the lesson
activity”
0 – 3 minutes
Introduction
Listening
Talking
3 – 10 minutes
Planning
Planning, brainstorming,
Listening, monitoring
discussing ideas
student group work
10 -30 minutes
Construction
Constructing the prototype Monitoring student work
bridge
30 – 40 minutes Testing
Testing bridges
Supervising testing
procedure
40 – 45 minutes Reflection
Talking
Listening, summarizing
10. Describe the homework you will assign. What guidance will you provide the students?
 The homework will be for students to assess the strengths and weaknesses of their own
design, and also that of at least one other group. and make at least one suggestion for a
modification they could make that would meet a different need/ solve a different
problem. This engages the students in the engineering design process. Discuss the
homework the next day so students can learn from the ideas of others. Students will be
instructed to think about how real world engineers apply the engineering design process
to the construction of bridges, and which types of engineers might work together on the
project. Students will also be asked to research one bridge that is famous for either being
a novel success or being a failure (Tacoma Narrows). They will need to consider which
types of engineers were involved in the design and construction of the bridge.
11. Teacher's Guide
 Make sure students are divided into effective groups. Group together students with
differing strengths. Make sure all group members are actively participating.
 Make sure students follow the engineering design process and plan before building.
 Ensure that you are familiar with the materials and their benefits/ pitfalls.
 With the homework, make sure students think about how many different types of
engineers might try to improve the bridge. Materials cost? More environmentally friendly
materials? Bridge performance (strength) enhancement? And so on. Make sure a full
class discussion of the homework assignment is included in a subsequent class period.
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Building a Bridge
Goal: Design and build a bridge that meets the design criteria below with the largest possible
strength to cost ratio (see below).
Design Criteria:
 The bridge must be at least 20” long and be able to span a gap of 12”
 Only materials listed below may be used.
Testing Criteria:
 Your bridge will be situated across a 12” gap between two adjacent desks. A cup will be
suspended from your bridge. Pennies will then be added to the cup, one at a time, until
any part of your bridge comes apart. The strength-to-cost ratio (the number of pennies in
the cup/the cost of your bridge in $) will be calculated.
Available materials and cost:
Material
Quantity Used
Cost per piece
Toothpicks
$0.10
Gumdrops
$0.10
Total (Quantity * Amount)
TOTAL COST:
Total number of pennies in cup before bridge breaks: ___________________________
Calculation of Strength-to-Cost Ratio:
Number of
Pennies in Cup:
Total cost:
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____________
=
_________________
Be sure to follow the Engineering Design Process and document your work:
Step Number
1: Identify the need or problem
2: Research the need or problem
3: Develop possible solutions
4: Select the best possible solution
5: Draw a prototype
6: Test and evaluate
7: Communicate the solution
8: Redesign
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Comments and Observations