Gum Drop Bridge
Spero
Gum Drop Bridge (1 period, Honors)
NJ Core Curriculum Standards
CCS Number
5.1.12.A.2
Topic
5.1 – Science Practices
A – Understand Scientific
Explanations
5.1.12.B.2
5.1 – Science Practices
B – Generate Scientific
Evidence Through Active
Investigations
5.1.12.B.3
5.1 – Science Practices
B – Generate Scientific
Evidence Through Active
Investigations
Empirical evidence is used to
construct and defend
arguments.
5.1.12.D.1
5.1 – Science Practices
D – Participate Productively
in Science
5.1.12.D.2
5.1 – Science Practices
D – Participate Productively
in Science
Science involves practicing
productive social interactions
with peers, such as partner
talk, whole-group discussions,
and small-group work.
Science involves using
language, both oral and
written, as a tool for making
thinking public.
8.2.12.B.1
8.2 – Technology
Engineering, Education, and
Design
B - Design: Critical Thinking,
Problem Solving, and
Decision-Making
8.2.12.C.3
8.2 – Technology
Engineering, Education, and
Design
C – Technological
Citizenship, Ethics, and
Society
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Description
Interpretation and
manipulation of evidencebased models are used to build
and critique
arguments/explanations.
Mathematical tools and
technology are used to gather,
analyze, and communicate
results.
Design and create a product
that maximizes conservation
and sustainability of a scarce
resource, using the design
process and entrepreneurial
skills throughout the design
process.
Evaluate the positive and
negative impacts in a design
by providing a digital
overview of a chosen product
and suggest potential
modifications to address the
negative impacts.
8.2.12.E.1
8.2 – Technology
Engineering, Education, and
Design
E – Communication ad
Collaboration
What Students Should Know
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Kinematics
Dynamics
Energy
Momentum
Rotational Dynamics
o Center of mass
o Torque
o Static Equilibrium
ISLE
The Engineering Design Process
Use the design process to
devise a technological product
or system that addresses a
global issue, and provide
documentation through
drawings, data, and materials,
taking the relevant cultural
perspectives into account
throughout the design and
development process.
Gum Drop Bridge
Spero
Goals of the Lesson
Conceptual
What kinds of
physics that you
know of are involved
in making a bridge?
Quantitative
Be able to
approximate the
center of mass of your
bridge.
How do you evaluate
resource needs of a
device?
Be able to evaluate
tensile strength of
bridge based on
break-weight.
How must bridge
pieces be arranged to
gain maximum
strength for least
material?
What kinds of
engineering
disciplines are
involved in making a
real bridge?
Be able to calculate
efficiency based on
mass of bridge versus
mass of hanging
objects.
Be able to use static
equilibrium situations
to calculate for the
mass of an object.
What kind of
functionality must a
real bridge have that
we are neglecting?
Procedural
Be able to use the
Engineering Design
Process to direct
assembly, testing,
and revising design.
Be able to work with
materials given (be
able to measure
physical quantities
using a meter stick or
other tools).
Be able to work
effectively with
others.
Implementing ISLE
for application
experiments.
Implementing the
Engineering Design
Process for cyclic
design-redesign.
Be able to plan ahead
before construction.
Epistemological
How do you know that
the center of mass of
your bridge is
measurable?
How can I improve my
design and make my
device functional and
economical in materials
and/or energy use?
How can I figure out
what types of physics
are needed to make
quantitative
predictions?
In what ways does the
Engineering Design
Process contribute to
learning?
Important Details/Connections
Physics Content

Rotational Dynamics
 Newton’s Laws
 Torque (rotational Newton’s Laws)
 Center of Mass
 Static equilibrium
 Young’s Modulus
Real Life Connections
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Designing and redesigning something based on feedback
Bridges you drive/walk across
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Defining material needs and uses
Potential Student Difficulties
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Calculating anything based on torque
Being able to come up with a method of finding the center of mass
Making sure gum drops do not crack open for too many toothpicks
Coming up with one plan in a large group (~5-6)
Resources
Environment
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Large work tables for groups of 5-6 students
Movable tables for a 12 inch gap for bridges to span
Equipment
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Bags of gum drops, boxes of toothpicks
Paper clips
Styrofoam cups (or other small equivalent)
Pennies
Rulers
Lesson Description
Today, as you can see from the bags up here, we are going to be working with gum
drops. I made sure to buy the extra disgusting ones so you won’t be tempted to eat your work. I
also have toothpicks for you to use in making your own gum drop bridge. The goal is to make a
bridge approximately 18 inches long that will span a 12-inch gap. You want your bridge to be as
strong as possible. How well you do will depend on your “strength index”. This will be an index
of the mass of your bridge and the mass of the amount of pennies it can hold before starting to
break. You want to use the least material to support the most weight.
You will have most of the class to work on the bridge, but expect to be finished with at
least 10 minutes left to test the strength of the bridge as well as measure the center of mass of the
bridge (which you will need to figure out how to do yourselves).
For homework check the website. Make sure you fill out the sheet with your pennies
held, mass of your bridge, and center of mass. (Make sure you keep the center of mass value for
yourself for homework.)
Gum Drop Bridge
Spero
Time Table
Clock Reading
During Lesson
Period 1
0-5 minutes
Title of Activity –
Connection to Goals
Goals and viewing
materials
5-30 minutes
Gum Drop Bridge
30-40 minutes
CM measurement &
Strength Testing
40-45 minutes
Cleaning Up
Students Doing
Teacher Doing
Listening to teacher,
going up to see
materials available.
Planning and building
bridge. Filling in
Engineering Design
Process. Coming up
with a way to measure
center of mass.
Measuring center of
mass and testing
strength of bridge.
Giving goals for the
day, handing around
materials.
Helping students
building the bridges.
Making sure students
come up with a way
to measure center of
mass of their bridge.
Helping students set
up bridge on tables
and giving them
pennies and cups.
Cleaning Up
Cleaning Up
Formative Assessments
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Do students know how to measure the center of mass of an object using rotational
dynamics understating?
Can students work cooperatively in order to come up with a design and then build it such
that the bridge is completed within the time limit?
Strength index of bridge.
Homework
Homework
With center of mass value, mass of your bridge, and knowing how much mass it takes to
break your bridge. Come up with a problem that a student in class could solve (quantitative) that
uses this information. Then solve it. Be sure to include any diagrams or pictures needed to
understanding the problem.
Read the section in the book on stress (Young’s Modulus) and estimate it’s value for your
bridge (what assumptions do you need to make?).
In the future we will be working with bridges like this again. If you could revise how you
made the bridge, what would you change? Why? How would this improve your strength index?
In your new design, list some features that a real bridge has that yours did not. It is
possible to add some of these features?
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