SCIENCE OF INNOVATION
Bionic Limbs
A Science Perspective (Grades 6–12)
Lesson plans produced by the National Science Teachers Association.
Video produced by NBC Learn in collaboration with the United States Patent and Trademark Office
and the National Science Foundation.
Background and Planning
About the Video
This video features Homayoon Kazerooni, Ph.D., a roboticist and professor of mechanical
engineering at the University of California at Berkeley. Dr. Kazerooni and his team at the
Berkeley Robotics and Human Engineering Laboratory are working on electrically powered
“exoskeletons,” which attach to the body (e.g., the legs) thus allowing people who are
paralyzed to “walk” again. The video discusses how these bionic devices and systems replicate
the functions of joints and muscles, and work with the human central nervous system to make
walking possible. It also mentions how inspiration leads to innovation and how the patent
process enables both protection of new ideas and the sharing of these ideas with other
scientists and engineers so that improvements in science and technology can be made and
sustained over time.
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Series opening
Introducing exoskeletons as robotic devices to aid paraplegics
Introducing Dr. Kazerooni
Dr. Kazerooni describes his inspiration for the exoskeleton project
Defining bionics and adapting knowledge of the human body to the exoskeleton
Showing how exoskeletons are analogous to human voluntary movement
Describing the components of the exoskeleton
How the exoskeleton works
Paraplegic Steven Sanchez describing injury and demonstrating exoskeleton
Other examples of bionic innovations from Dr. Kazerooni’s lab
Role of the patent process in protecting and sharing ideas
Conclusion
Closing credits
Language Support To aid those with limited English proficiency or others who need help
focusing on the video, make available the transcript for the video. Click the Transcript tab on
the side of the video window, then copy and paste into a document for student reference.
Framework for K–12 Science Education
LS1.A: Structure and Function
PS2.A: Forces and Motion
PS2.B: Stability and Instability in Physical Systems
ETS1.A: Defining and Delimiting Engineering Problems
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ETS2.A: Interdependence of Science, Engineering, and Technology
ETS2.B: Influence of Engineering, Technology, and Science on Society and the Natural World
Emphasize Innovation
The Innovation Process
Inspiration Dr. Kazerooni’s inspiration for his initial ideas that sparked his innovations is rooted
in his observations of problems around us. Dr. Kazerooni’s earlier work was for the military,
developing exoskeletons, such as the “ExoHiker,” “ExoClimber,” and the “Human Universal
Load Carrier” (HULC) to help soldiers carry heavy loads. This experience laid the groundwork for
a “natural progression from the military to the medical,” as he stated in the July/August 2012
issue of IEEE Pulse, which can be accessed at the URL below. He also saw a potential link
between the engineering of humanoid robots and solving the problem of enabling people who
are physically impaired to walk.
IEEE Pulse: http://bionics.soe.ucsc.edu/publications/EMB_Pulse_Magazine_Exoskeleton.pdf
Take Action with Students Have students discuss their own observations of problems around
us (of any level of complexity or severity) that might be addressed or solved with a new
technology pertaining to bionic limbs. Encourage their inspirations with a “sky’s the limit”
brainstorming session where any and all ideas are put on the table. Extend the discussion of
some ideas to identify the science and math concepts that would support the technology.
Innovation and STEM
The innovation highlighted in Science of Innovation (SOI): Bionic Limbs incorporates many
aspects of STEM (Science, Technology, Engineering, and Mathematics). For example, required
science knowledge includes an understanding of the role of the human central nervous system
in voluntary movement and the relationship of the purposes of bones, muscles, and joints for
strength and range of motion. Math concepts revolve around programming and the geometry
needed to create angles that give the appropriate range of motion for the analogous body part.
Starting with a vision and relying on science and math knowledge, this technology enables
people to extend their natural capabilities by making an analogous relationship between how
some parts of the human body work and robotic function. The engineering design process
involved is limited by constraints related to materials, time, and costs. Among the constraints
Kazerooni’s team is working with are keeping the weight of the apparatus to a minimum and
minimizing cost to make it affordable to a greater number of people.
Take Action with Students
 Using the Design Investigations section of Facilitate Inquiry as a guide, encourage students
to investigate how muscles connect to bones (or how actuators connect to robotic
exoskeletons), and how to maximize strength and efficiency.
 Point out the volunteer patient Steven Sanchez’s statement near the beginning, “A very
spiritual feeling... I’m as tall as you guys again.” Have students compare the definitions of
the words empathy and sympathy to help them understand the importance of empathy in
the innovation process. Then encourage them to write personal journal entries on what
they heard and saw in the video, to make them think about the interactions with people
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with disabilities. Suggest that they think about their career aspirations and consider how
their feelings might lead to a STEM-focused career that results in enhancements to peoples’
lives that are similarly “spiritual.”
Facilitate Inquiry
Encourage inquiry using a strategy modeled on the research-based science writing heuristic. Student
work will vary in complexity and depth depending on grade level, prior knowledge, and creativity. Use
the prompts liberally to encourage thought and discussion. Student Copy Masters begin on page 8.
Explore Understanding
Many students might not have given much thought to how their muscles function in concert
with their joints to generate force, or more specifically torque. Torque produces rotational
motion and is key to how the exoskeleton system works. Torque is defined as the lever arm
length multiplied by the component of force perpendicular to the lever arm). To get students
thinking about the torque necessary to cause rotational movement, demonstrate how turning a
bolt using a wrench with a short handle compares to turning the same bolt with a long-handled
wrench. In order to create functioning exoskeletons, researchers must carefully model the
motions of actual limbs, and must connect the motors, or “actuators,” to these limbs to work as
efficiently as possible and to generate sufficient torque. Have students pull on elastic exercise
bands using their biceps muscle at different angles, to see at what angles they can exert the
most force or torque (rotational motion), or exert a specific force most comfortably. Then use
these or similar prompts to spark a discussion about muscular actions required for movement.
 The biceps moves the forearm by….
 The biceps acts as an actuator by….
 The angle at which it was easiest to stretch a band or lift a weight was….
 The angle of the forearm at which the most force is generated was….
Show the video SOI: Bionic Limbs. Continue the discussion of exoskeletons, using prompts such
as the following:
 When I watched the video, I thought about….
 The expert in the video was inspired to create exoskeletons by….
 The brain, nerves, joints, and muscles are simulated by….
 The purpose of the forearm crutches is….
 The motors used to operate the joints are called….
 Patents enable the patent-holder to….
Ask Beginning Questions
Stimulate small-group discussion with the prompt: This video makes me think about these
questions…. Then have groups list questions they have about the challenges that must be
surmounted in order to maximize the strength and efficiency of exoskeletons. Ask groups to
choose one question and phrase it in such a way as to be researchable and/or testable. The
following are some examples.
 How are the actuators connected to the limbs?
 How are these actuators similar to, or different from, human muscles?
 What differences are there between hip and knee joints in a human? In the exoskeleton?
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Design Investigations
Choose one of the following options based on your students’ knowledge, creativity, and ability level and
your available materials. Actual materials needed will vary greatly based on these factors as well.
Possible Materials Allow time for students to examine and manipulate the materials you have
available. Doing so often aids students in refining their questions or prompts new ones that
should be recorded for future investigation. In this inquiry, students might use materials such as
wooden meter sticks, wooden rulers, or other wooden sticks as “bones;”; strings as “tendons;”;
and spring scales or rubber bands as “muscles.” Include tape, nuts and bolts, nails, pegs, or
other tools to attach the sticks together. The rulers or meter sticks described in the Focused
Approach have holes drilled along their length. Students will also need protractors to measure
angles. Students might also use commercially available building sets, such as the mechanical
dog available from http://www.scientificsonline.com/mechanical-dog-robot-kit.html.
Safety Considerations To augment your own safety procedures, see NSTA’s Safety Portal at
http://www.nsta.org/portals/safety.aspx.
Open Choice Approach (Copy Master page 8)
Groups might come together to agree on one question for which they will explore the answer,
about how they might maximize the strength and efficiency of exoskeletons, or each group
might explore something different. Students should brainstorm to form a plan they would have
to follow in order to answer the question, which might include researching background
information. Work with students to develop safe procedures that control variables and enable
them to gather valid data. Encourage students with prompts such as the following:
 Information we need to understand before we can start our investigation is….
 The variable we will test is….
 The variables we will control are….
 The steps we will follow are….
 To conduct the investigation safely, we will….
Focused Approach (Copy Master pages 9–10)
The following exemplifies how students could investigate how muscles connect to bones (or
how actuators connect to robotic exoskeletons), and how to maximize strength and efficiency.
1. After students examine the materials you have available to construct a simple joint, ask
them questions such as the following to help them envision their investigation.
 How can we make a model of the human arm from these materials?
 In our model, what will function as bones, joints, and muscles?
 What are some possible variables we can investigate?
 How could we hold certain variables constant while manipulating others?
 How many variables should we allow to vary at a time?
 How can we measure force?
2. Students might use two rulers or meter sticks connected in an L shape: one for the upper
arm and one for the forearm. Students can then consider how and where to attach a string
to the forearm, and where it can go from there. A good option is to tie the string through
other pre-drilled holes in the “forearm,” and then pass it over a smooth peg near the top
end of the vertically positioned “forearm.” The string could then be attached to a spring
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3.
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scale or digital force sensor, hooked masses from a large set of known masses, or to a
rubber band. Students could make the rubber bands into not only force-applying devices,
but also force-measuring devices, by hanging known masses from them, measuring the
length under tension, and making a graph of force versus length. NOTE: This might be an
opportunity to review or discuss the differences and connections between mass and weight,
especially if this is being done in a physics class. Guide students to understand how their
arrangement does or does not resemble the joints in the video.
Once students have created a model of an arm, guide them to practice executing a series of
motions with it, perhaps using standard hooked masses hanging from the “forearm” to vary
the resistance. They might start with the upper arm vertical and the forearm horizontal, but
later, change one or more of these conditions. Use the following prompts to guide students
in their thinking.
 This arm model is an example of a first class lever, which means….
 Attaching the string further from the “elbow” joint might reduce the required force
needed to lift an object because…. (Note: This would be expected because a longer lever
arm gives more mechanical advantage, or—in the case of this third class lever, less
mechanical “disadvantage,” one might say)
 Attaching the string further from the “elbow” joint might increase the required force
needed to lift an object because…. (Note: As the string is placed further from the joint, it
becomes less perpendicular to the forearm, and therefore would produce less torque
with a given lever arm length, BUT students will probably find that this factor is less
important, so that increasing distance from the joint is a net “positive.”)
 Making the forearm more vertical makes the arm “stronger”/”weaker” because….
 Making the upper arm more vertical makes the arm “stronger”/”weaker” because….
Ensure that students brainstorm to decide what to hold constant, what to vary, and how to
measure the force. Use prompts like these to guide them in their thinking:
 The best way to hold force constant is….
 The best way to hold the angle between the segments constant is….
 The dependent (responding) variable and the independent (manipulated) variable could
be….
 To conduct the investigation safely, we will….
Students might continue their investigation by varying the orientation of the forearm
and/or upper arm. They might also think of ways to change the direction of the resistance
(which by default tends to be vertical, if it consists of the weight of the forearm stick and
any masses possibly hanging from it).
Students can use the Internet or other resources to find where the biceps tendon is actually
attached to the forearm (to which bone) in humans and how this compares with the
positions used in the arm model they have been working with. Students can then use their
graphed data, along with comparisons with tendon placement in a human arm, to estimate
the actual force exerted by (and therefore tension in) the biceps tendon when a person is
holding a certain weight with the forearm horizontal and upper arm vertical. Encourage
students to include labeled diagrams that show an understanding of the physics involved in
the bionic motions they modeled.
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Media Research Option
Groups might have questions that are best explored using print media and online resources.
Students should brainstorm to form a list of key words and phrases they could use in Internet
search engines that might result in resources that will help them answer the question. Review
how to safely browse the Web, how to evaluate information on the Internet for accuracy, and
how to correctly cite the information found. Suggest students make note of any interesting
tangents they find in their research effort for future inquiry. Encourage students with prompts
such as the following:
 Words and phrases associated with our question are….
 The reliability of our sources was established by….
 The science and math concepts that underpin a possible solution are….
 Our research might feed into an engineering design solution such as….
 To conduct the investigation safely, we will….
Make a Claim Backed by Evidence
Students should analyze their data and then make one or more claims based on the evidence
their data shows. Encourage students with this prompt: As evidenced by… we claim… because….
An example claim might be:
As evidenced by the reduced tension in the “tendon” when attached far from the elbow, we
claim that the greatest ability to lift weight occurs with this attachment position because this
produces a longer lever arm, which increases the torque.
Compare Findings
Encourage students to compare their ideas with those of others, such as classmates who
investigated a similar question or system or with those that investigated a different question or
system, material they found on the Internet, an expert they chose to interview, or their
textbooks. Remind students to credit their original sources in their comparisons. Elicit
comparisons from students with prompts such as the following:
 My ideas are similar to (or different from) those of the experts in the video in that….
 My ideas are similar to (or different from) those of my classmates in that….
 My ideas are similar to (or different from) those that I found on the Internet in that….
Students might make comparisons like the following:
My findings on what maximizes arm strength are different from actual human anatomy,
because a tendon attached too far from the elbow would not fit under the skin and would offer
less range of motion, in spite of increased strength.
Reflect on Learning
Students should reflect on their understanding, thinking about how their ideas have changed or
what they know now that they didn’t before. Encourage reflection, using prompts such as the
following:
 The claim made by the expert in the video is….
 I support or refute the expert’s claim because in my investigation….
 When thinking about the expert’s claims, I am confused as to why….
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
Another investigation I would like to explore is….
Inquiry Assessment
See the rubric included in the student Copy Masters on page 11.
Incorporate Video into Your Lesson Plan
Integrate Video in Instruction
Bellringer On a day when your lesson focus is bones and joints, play the video as students are
getting settled. Have students note two ways the exoskeleton is like their endoskeleton. Use
their observations as a springboard for points in your lesson.
Compare/Contrast Have students compare and contrast Dr. Kazerooni’s robotic exoskeleton
with the more familiar exoskeleton of arthropods.
Using the 5E Approach?
If you use a 5E approach to lesson plans, consider incorporating video in these Es:
Explore Students might investigate walking components by playing with the online game
“QWOP,” at http://www.foddy.net/Athletics.html. This rather challenging game uses the
keyboard letters Q, W, O, and P to control the motions of a character’s right and left thighs and
calves, to try to run a 100-meter sprint.
Elaborate Have students identify the neurological issue that resulted in volunteer patient
Steven Sanchez’s paralysis. Brainstorm with students a list of factors that might make Steven a
good research volunteer for this project. Then have students research other conditions that
result in paralysis that might or might not be able to take advantage of the exoskeleton.
Connect to … Social Studies
Debate Refer students to the article “Better Than Human: Why Robots Will—And Must—Take
Our Jobs,” in the January 2013 issue of Wired Magazine. Have students use the information in
the article, plus other references, if needed, to discuss the positive and negative impacts robots
might have on future societies and economies. Divide the class into three teams: one that will
argue in favor of the stated topic, one that will argue against it, and one that will act as the
audience. Have students work together to arrange ideas for their team’s arguments and for
refuting the other team’s arguments. The audience might do research about the topic in order
to ask relevant questions. Hold the debate by allowing for arguments and rebuttals, back and
forth until all members of both teams have had the opportunity to speak at least one time.
When the debate has ended, ask the audience to determine which team “won” and why.
Remind students to base their vote on evidence presented in the debate only, not their
personal opinion of the topic that was debated. Was there one specific argument that
convinced them that one team won?
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Prompt Innovation with Video
After students watch the video, have them research patents associated with exoskeletons and
bionic limbs. They can do so with an Internet search on Google.com/patents using search terms
such as the following. If time is limited, point students toward the following patents.
Primary Search Terms
Gait/Step
Mechanical joint
Biological joint
Paraplegic
Paralysis
Prosthetic
Orthosis
Actuator
Motor/Motorized
Additional Helpful Search Terms
Handicap
Disability
Robot/Robotic
Limb
Amputee
Muscle Assistance
Mobility Assistance
Brace
Controller
Propulsion
Sensor/Detector
Patent Examples
5,020,790 – powered apparatus to assist with walking motion
5,282,460 – exoskeletal robotic device
5,476,441 – apparatus providing controlled limb movement
6,500,210 – method for providing sensory perceptions in a sensor system of a prosthetic device
6,676,707 – prosthesis for a limb
6,807,869 – sensor for detecting presence of a force exerted by a person’s foot on a surface
7,041,074 – device for users with central nervous system injuries, handicaps, etc.
7,947,004 – lower extremity exoskeleton
Suggest students read abstracts of patents that attract their attention. Then hold a discussion
about how various innovators are improving on the process. Use prompts such as the following:
 This patent is for _____, which is related to the invention shown in the video by….
 This patent describes _____, which differs from the invention shown in the video in that….
 I think doing/making _____ would be an innovation because ….
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COPY MASTER: Open Choice Inquiry Guide for Students
Science of Innovation: Bionic Limbs
Use this guide to investigate a question about how you might maximize the strength and
efficiency of exoskeletons. Write your lab report in your science notebook.
Ask Beginning Questions
The video makes me think about these questions….
Design Investigations
Choose one question. How can you answer it? Brainstorm with your teammates. Write a
procedure that controls variables and makes accurate measurements. Look up information as
needed. Add safety precautions.
 Information we need to understand before we can start our investigation is….
 The materials I will use are….
 The variable I will test is….
 The variables I will control are….
 The steps I will follow are….
 To conduct the investigation safely, I will….
Record Data and Observations
Record your observations. Organize your data in tables or graphs as appropriate.
Make a Claim Backed by Evidence
Analyze your data and then make one or more claims based on the evidence your data show.
Make sure that the claim goes beyond summarizing the relationship between the variables.
My Evidence
My Claim
My Reason
Compare Findings
Review the video and then discuss your results with classmates who investigated the same or a
similar question. Or do research on the Internet or talk with an expert. How do your findings
compare? Be sure to give credit to others when you use their findings in your comparisons.
 My ideas are similar to (or different from) those of the experts in the video in that….
 My ideas are similar to (or different from) those of my classmates in that….
 My ideas are similar to (or different from) those that I found on the Internet in that….
Reflect on Learning
Think about what you found out. How does it fit with what you already knew? How does it
change what you thought you knew?
 The claim made by the expert in the video is….
 I support or refute the expert’s claim because in my investigation….
 When thinking about the expert’s claims, I am confused as to why….
 Another investigation I would like to explore is….
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COPY MASTER: Focused Inquiry Guide for Students
Science of Innovation: Bionic Limbs
Use this guide to investigate the muscles and bones used in a simple model of a human arm.
Write your lab report in your science notebook.
Ask Beginning Questions
Where on the forearm should the biceps tendon be attached to maximize the amount of weight
that can be held by a robotic forearm?
Where should this tendon be attached to maximize the range of motion of the elbow joint?
Design Investigations
Brainstorm with your teammates about how to answer the question. Write a procedure that
controls variables and allows you to gather valid data. Draw pictures to illustrate your designs.
Add safety precautions as needed. Use these prompts to help you design your investigation.
 The “shoulder” will be represented by….
 The “elbow” will be represented by….
 The steps I will follow to measure the tension in the “biceps tendon” are….
 The independent variable(s) I will be manipulating are….
 The best way to display the data I gather is….
 To conduct the investigation safely, I need to….
Record Data and Observations
Organize your observations and data in a table. The table below is a simple example of how you
might record the dependent variable Tension as a function of the independent variables,
distance from elbow and angle between forearm and upper arm. You might first hold the angle
constant at 90 degrees while varying the attachment point, and then hold attachment point
constant while varying the angle, perhaps from about 30 to 150 degrees.
How Tendon Tension Varies With Distance from Elbow and Angle
Between Upper Arm and Forearm.
Angle Between Upper Arm
and Forearm
Distance of Tendon
Attachment from Elbow
SOI: Bionic Limbs, A Science Perspective (Grades 6–12)
Tension in “Tendon”
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Focused Inquiry Guide continued
Graph the Data
Plot tension versus distance of attachment from elbow for a 90 degree angle between upper
arm and forearm, and then plot tension versus angle for a given (mid-range) attachment
distance. More combinations can be tried, to produce multiple curves on each graph, if time
permits.
Tension
Distance of Attachment
Make a Claim Backed by Evidence
Analyze your data and then make one or more claims based on the evidence shown by your
data. Make sure that the claim goes beyond summarizing the relationship between the
variables.
My Evidence
My Claim
My Reason
Compare Findings
Review the video and then discuss your results with classmates who did the investigation using
the same or a similar system or with those who did the investigation using a different system.
Or do research on the Internet or talk with an expert. How do your findings compare? Be sure
to give credit to others when you use their findings in your comparisons.
 My ideas are similar to (or different from) those of the experts in the video in that….
 My ideas are similar to (or different from) those of my classmates in that….
 My ideas are similar to (or different from) those that I found on the Internet in that….
Reflect on Learning
Think about what you found out. How does it fit with what you already knew? How does it
change what you thought you knew?
 The claim made by the expert in the video is….
 I support (or refute) the expert’s claim because in my investigation….
 When thinking about the expert’s claims, I am confused as to why….
 Another investigation I would like to explore is….
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COPY MASTER: Assessment Rubric for Inquiry Investigations
Criteria
Initial question
Investigation
design
Variables
Safety procedures
Observations and
data
Claim
Findings
comparison
Reflection
1 point
Question had a yes/no
answer, was off topic, or
otherwise was not
researchable or testable.
2 points
Question was
researchable or testable
but too broad or not
answerable by the
chosen investigation.
The design of the
While the design
investigation did not
supported the initial
support a response to
question, the procedure
the initial question.
used to collect data
(e.g., number of trials,
control of variables)
was not sufficient.
Either the dependent or
While the dependent
independent variable
and independent
was not identified.
variables were
identified, no controls
were present.
Basic laboratory safety
Some, but not all, of the
procedures were
safety equipment was
followed, but practices
used and only some
specific to the activity
safe practices needed
were not identified.
for this investigation
were followed.
Observations were not
Observations were
made or recorded, and
made, but were not
data are unreasonable in very detailed, or data
nature, not recorded, or
appear invalid or were
do not reflect what
not recorded
actually took place during appropriately.
the investigation.
No claim was made or
Claim was marginally
the claim had no
related to evidence
relationship to the
from investigation.
evidence used to support
it.
Comparison of findings
Comparison of findings
was limited to a
was not supported by
description of the initial
the data collected.
question.
Student reflections were
limited to a description
of the procedure used.
Student reflections
were not related to the
initial question.
SOI: Bionic Limbs, A Science Perspective (Grades 6–12)
3 points
Question clearly stated,
researchable or testable,
and showed direct
relationship to
investigation.
Variables were clearly
identified and controlled
as needed with steps and
trials that resulted in data
that could be used to
answer the question.
Variables identified and
controlled in a way that
results in data that can be
analyzed and compared.
Appropriate safety
equipment used and safe
practices adhered to.
Detailed observations
were made and properly
recorded and data are
plausible and recorded
appropriately.
Claim was backed by
investigative or research
evidence.
Comparison of findings
included both
methodology and data
collected by at least one
other entity.
Student reflections
described at least one
impact on thinking.
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