SCIENCE OF INNOVATION
Bionic Limbs
An Engineering 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 Information
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.
0:00
0:15
0:51
1:14
1:41
2:07
2:22
2:58
3:24
4:10
4:28
4:55
5:10
0:14
0:50
1:13
1:40
2:06
2:21
2:57
3:23
4:09
4:27
4:54
5:09
5:22
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
LS1.D: Information Processing
ETS1.A: Defining and Delimiting Engineering Problems
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
1
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 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 design an exoskeleton that will enable a rag doll to walk in a coordinated fashion.
 Use the video as a springboard to start students talking about the wide range of activities
scientists and engineers participate in and the environments in which they work. Play the
video with the sound muted and ask volunteers for their thoughts about the lab
environment they are viewing, the way that everyone is dressed, what types of people, in
terms of their careers, they think might be involved in the design and manufacture of bionic
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
2

limbs, what they think the working environment might be like, and so on. Encourage
students to point out specific people and specific jobs being done and comment on what
kind of science knowledge, technical abilities, or other expertise individuals might need to
work there.
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. 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 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
Most students are probably not conscious of the complex symphony of actions needed for
everyday movement, such as walking. In order to create functioning exoskeletons, researchers
must carefully model the motions of actual limbs, and then create the hardware and software
necessary to replicate these. If possible, have students instruct each other on how to walk,
using only motions of the thighs (hip joints) and calves (knee joints) to form commands, such as
“right thigh forward” or “left calf backward” (i.e., a combination of left/right, thigh/calf, and
forward/backward). After this potentially entertaining activity, use these or similar prompts to
spark a discussion about the sequence of muscular actions required for walking.
 I would instruct someone to use their legs in walking by saying….
 I would instruct someone in using their thighs to walk by saying….
 I would instruct someone to use their calves in walking by saying….
 The correct sequence of instructions for walking is….
 Humans are able to walk because all of these instructions are processed by the….
Show the video “SOI: Bionic Limbs”. Continue the discussion of walking while using
exoskeletons, with 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 in the exoskeleton by….
 The forearm crutches aid walking by….
 Devices similar to the exoskeleton for walking include….
 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
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
3
surmounted in order to create functional exoskeletons for walking. 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.
 What movements must be controlled in order to walk?
 How must movements be coordinated in order to walk?
 How might the computer assist in coordinating the motions of the various actuators?
 How might a computer develop a map of instructions on how to walk? How could you draw
a flow chart to describe the steps involved in walking?
 How much control does the user have over the specific motions?
 How much control should the user have over the specific motions?
 What factors would determine whether or not an exoskeleton would be preferable to a
motorized wheelchair?
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
rag dolls, craft sticks, tape, washers, bolts, nuts, and weights. The craft sticks described in the
Focused Approach have holes drilled near the ends. Students might also benefit from having
protractors available for measuring angles.
NOTE: A single additional craft stick, with both “thighs” connected at the same point (with extra
washers to keep the legs from hitting each other) could function as a “torso,” if the dolls are not
available or if time is limited.
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,
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 exoskeleton device we are designing will….
 The exoskeleton will move via….
 The actions the exoskeleton will accomplish are….
 To conduct the investigation safely, we will….
Focused Approach (Copy Master pages 9–10)
The following exemplifies how students could design an exoskeleton that transforms a rag doll
into a marionette and coordinates movements to enable it to “walk.”
1. After students examine the materials you have available to construct simple systems, ask
them questions such as the following to help them envision their investigation.
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
4






For a single doll, how many craft sticks are needed to make an exoskeleton?
How will the exoskeleton be attached to the doll?
What joints can be constructed, and how?
To mimic human walking, which joints cannot swing past a certain point?
What sequence of actions will enable the doll to “walk”?
Does one action need to be completed before another is started, or can/should actions
overlap?
2. Students might use constructions such as two craft sticks: one for the thigh and one for the
calf, with two washers, a bolt, and a nut serving as a “knee” joint. Other joints might be
constructed similarly. Tape can be used to attach the craft sticks to the doll. Guide them to
understand how their arrangement does or does not resemble the exoskeletons in the
video.
3. Once students have created an exoskeleton for their doll, explain that they need to attach
strings from the joints to guide bars that enable them to manipulate the exoskeleton in
executing motions, similarly to how the actuators enable manipulating the exoskeleton for
people. Use prompts such as the following to guide students in their thinking.
 The first motion needed is….
 The doll will fall over unless….
 Actions that cannot be performed at the same time include….
 The last step in the series before returning to the first motion is….
4. Ensure that students brainstorm to formulate a list of all the actions needed to complete a
full step. Students might devise a number of different ways to represent these actions, such
as a linear sequence of all events, where different actions are represented on different
rows, with a common time scale:
 The best way to display or list these steps is….
 Symbols we might use for the actions are….
 Alternative ways of walking that might still be successful include….
 To conduct the investigation safely, we will….
5. Students might continue their investigation by constructing flowcharts with instructions on
how to walk, run, and/or having the dolls compete in a race.
6. Some students might wish to extend their investigation 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. Optionally, have students engage in friendly
competition to see who can run the farthest playing QWOP.
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….
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
5




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 inability of the doll to take multiple steps using only hip motions, we claim
that both hip and knee joint motions are necessary for walking because without bending the
knee joint, the leg in the back cannot swing forward.
Compare Findings
Encourage students to compare their ideas with 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:
 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 ideas are similar to those discussed by researchers, published on the Internet, who have
done detailed studies of walking. I found that the knee joint must bend at the correct time as the
hip joint rotates, so that the foot can clear the ground.
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….
 Another investigation I would like to explore is….
Inquiry Assessment
See the rubric included in the student Copy Masters on page 11.
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
6
Incorporate Video into Your Lesson Plan
Integrate Video in Instruction
Visualize Concepts Use the video to support a discussion on how neural pathways are involved
in human motion. Have students focus on the central portion of the video (2:07-2:21) and then
construct diagrams that compare the human body and the robotic exoskeleton.
Homework Have students choose various components of exoskeletons to research individually
(or as part of small teams) so they can share their findings with the class the next day. These
items could include “actuator,” “servomotor,” “power supply,” and “carbon fiber.”
Using the 5E Approach?
If you use a 5E approach to lesson plans, consider incorporating video in these Es:
Explain Use the Design Investigations section of the Facilitate Inquiry to support your lessons
on torque or mechanical advantage.
Elaborate Robotic devices replace or augment humans in many industrial situations. Use the
video to encourage students to learn more about some of the many factors that determine how
useful the robotic exoskeleton might or might not be. These include cost, weight, comfort,
versatility, and the psychological benefit of being able to face others eye-to-eye instead of
always having to look up at standing people. Students also might be interested in reading the
article on future robotics systems, in the January 2013 issue of Wired Magazine, to consider the
similarities and differences among, for example, robots designed to teach, those designed for
use in the medical field, those designed for factory work, and so on.
Connect to … Math
Trigonometry Use either the rag doll exoskeleton—or a simpler version with the doll absent,
but the hip joints of the two “thighs” connected by a “torso” craft stick—to collect data on the
angles (from the neutral, vertical position) at which the leg and calf extend from their
respective (hip and knee) joints. Graph these angles versus the point in the step cycle, for both
legs. Discuss this in the context of periodic functions such as sine waves. This is most
appropriate for older high school students who have had or are taking math courses
incorporating trigonometry. Compare to similar, but rather sophisticated, analyses in the
following sources:
 http://www.ipcsit.com/vol8/5-S1.8.pdf
 http://ruina.tam.cornell.edu/research/topics/locomotion_and_robotics/simplest_walking/s
implest_walking.pdf
 http://www.engin.umich.edu/class/me646/HW04/MochonMcMahon.pdf
 http://groups.csail.mit.edu/robotics-center/public_papers/Hsu07.pdf
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
7
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 improves on the process we observed in the video by….
 This patent describes _____, which differs from the invention shown in the video in that….
 I think doing _____ would be an innovation because….
 I think if we did ...., it would improve the walking robot because....
 I think if we did …., it would improve an athlete robot because….
 I think if we did …., it would improve a teacher robot because….
 I think if we did …., it would improve a nurse robot because ….
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
8
COPY MASTER: Open Choice Inquiry Guide for Students
Science of Innovation: Bionic Limbs
Use this guide to investigate a question about exoskeletons, how the user might best control
them, or factors that affect the usefulness of such devices. 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 exoskeleton device we are designing will….
 The exoskeleton will move via….
 The actions the exoskeleton will accomplish are….
 To conduct the investigation safely, we 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….
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
9
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
10
COPY MASTER: Focused Inquiry Guide for Students
Science of Innovation: Bionic Limbs
Use this guide to investigate the cycle of thigh and calf motions used in a simple model of
walking. Write your lab report in your science notebook.
Ask Beginning Questions
What sequence of thigh and calf motions is needed in order for either a robot or a human to
walk?
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. Add safety precautions as needed. Use
these prompts to help you design your investigation.
 The system I will use is _____.
 The number of joints needed for each leg is….
 The angles of the limb segments will be measured from….
 The steps I will follow to measure these angles include….
 The joints that can swing in only one direction from the “straight” (zero) position are the….
 The best way to display these angles as they change with the part of the walking cycle is….
 To conduct the investigation safely, I need to….
Record Data and Observations
Organize your observations. You might do this be using a smart phone to video an individual
and then translate that into a step-by-step. Or, you might record data in a table such as the one
below that shows how the angles of the limb segments change with percentage of the way
through a whole step cycle (when both legs have swung and are back in the original position).
Pick a direction (forward or backward) to be the positive one, the other direction being called
negative. Think in advance about how many positions in the cycle (from 0 to 100%) will be
sufficient to accurately describe the sequence of motions.
How Limb Angles Change With Percentage of Way Through Step Cycle
Sketch of
phase in the
step cycle
Percentage of
way through a
whole step cycle
Angle of Right
Thigh to Torso
Line
Angle of Left
Thigh to Torso
Line
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
Angle of Right
Calf to Right
Thigh Line
Angle of Left
Calf to Left
Thigh Line
11
Focused Inquiry Guide continued
Graph the Data
Plot each limb’s angle on the vertical axis of a graph, whose horizontal axis is a percentage of
the step cycle, going from 0 to 100%. Make each limb’s plot a different color. Be sure to allow
room for negative angles if needed.
Angles (o) of
Limbs
100%
0%
Percentage of Step Cycle
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….
SOI: Bionic Limbs, An Engineering Perspective (Grades 6–12)
12
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, An Engineering 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.
13