Making and Breaking Bones: Learning Physics through Engineering Design

Abstract

Eighth grade students in an engineering course designed and tested prosthetic bones for use in a movie. Bone design required physics content to be integrated with knowledge of math, engineering, and technology. Specifically, students used a 3D printer and associated design software to design, fabricate, and test a prosthetic fibula for a stuntman's use in a movie. This paper explains how the project motivated students' use of physics content and further required students to use their knowledge of physics (e.g., force, motion, and pressure) in coordination with other content knowledge.

Full text

Making and breaking bones: learning physics through engineering design
Alexandria K. Hansen, and Danielle B. Harlow
Gevirtz Graduate School of Education, University of California, Santa Barbara, 93106-9490
Eighth grade students in an engineering course designed and tested prosthetic bones for use in a movie.
Bone design required physics content to be integrated with knowledge of math, engineering, and
technology. Specifically, students used a 3D printer and associated design software to design, fabricate, and
test a prosthetic fibula for a stuntman’s use in a movie. This paper explains how the project motivated
students’ use of physics content and further required students to use their knowledge of physics (e.g., force,
motion, and pressure) in coordination with other content knowledge.
I. INTRODUCTION
Digital fabrication and design (e.g., 3D printing) is
emerging as an engaging approach to combine the
disciplines of Science, Technology, Engineering, and
Mathematics (STEM) in K-12 education. Research in this
area has focused on increasing participation in STEM [1],
identity [2], and access for underrepresented populations
[3,4]. We focus on how these types of activities provide
alternative opportunities for students to learn physics
content. Specifically, we look at how a design challenge to
design, print, and test a prosthetic bone for use as a movie
prop provided opportunities for students to learn about
density, forces, and materials.
Two movements in education are relevant to our work:
The Next Generation Science Standards (NGSS) and the
Maker Movement. The NGSS [5] describe a vision of K-12
science education that differ from previous standards in that
teachers must actively engage students in learning science
content through the practices of professional scientists and
engineers: practices such as asking questions, developing
models, and constructing scientific explanations and
engineering solutions. Additionally, the NGSS explicitly
includes engineering design as content to learn about and is
integrated into performance expectations for physics and
the other sciences. Including engineering was done in an
effort to improve how students from underrepresented
populations identify with science and to offer opportunities
for innovation and creativity at the K-12 level [5]. While
the intention is that students will interact with and learn
science content knowledge while solving these engineering
problems, research in this area is limited.
Coupled with this change in schools, the “Maker
Movement” has influenced both informal (e.g., museums,
libraries) and formal education (school) settings, and has
been endorsed by the White House as a legitimate means of
increasing STEM participation [6]. This movement
“represents a growing movement of hobbyists, tinkerers,
engineers, hackers, and artists committed to creatively
designing and building material objects for both playful and
useful ends” [7]. By providing opportunities for active
construction in STEM-rich contexts, students have the
power to transcend their role as technological consumers,
and become producers of technological artifacts and of their
own knowledge, skills, and learning experiences [4].
While making is not synonymous with engineering, the
ideas are related. Engineering includes specific design goals
and constraints as well as mathematical tests to optimize
among competing designs. Learning science content
through engineering may potentially create opportunities in
which students want to learn more disciplinary content in
order to complete a design. Moreover, productive design
challenges may provide opportunities for students to both
learn science content explicitly and “bump up against”
additional STEM content [8]. For example, in order for a
student to complete a design that involves using LEDs, they
must learn about electricity and circuits but they may also
learn about other content, depending on the design
challenge and design. The design challenge precedes the
need to know certain content, and provides a motivating
context in which to learn the necessary content to complete
the design.
This paper reports on a qualitative, case study of an 8th
grade Creative Design & Engineering Course in which the
teacher used digital fabrication to combine the disciplines
of STEM in an engaging manner, and provided
opportunities for students to “bump up against” physics
content [8] without explicit instruction. The paper is
organized as follows. An overview of the research context
and methods are described, followed by findings that
highlight the opportunities for learning physics content
when participating students engaged in a digital fabrication
project.
II. STUDY DESIGN AND CONTEXT
This study took place in an 8th grade Creative Design and
Engineering course at a small private school. It was a
required course for all students and was taught by the
school science teacher (Ms. Taylor) and an aide (Ms.
Wilson). 14 of 15 enrolled students agreed to participate in
this study: 7 male and 7 female. All student and teacher
names used in this report are pseudonyms.
edited by Jones, Ding, and Traxler; Peer-reviewed, doi:10.1119/perc.2016.pr.029
Published by the American Association of Physics Teachers under a Creative Commons Attribution 3.0 license.
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2016 PERC Proceedings,

In the year prior to this study, Ms. Taylor offered a
similar course, but a greater number of male students
elected to enroll than female students. Because the school
and teacher felt that this was an essential learning
experience for all students, the course was made mandatory
in the following academic year, resulting in more equal
gender distribution.
In the course, the teacher provided experiences for
students to design both digitally and physically. For
example, students programmed interactive stories and
games using Scratch (http://scratch.mit.edu), built robots,
experimented with a Makey Makey device
(http://makeymakey.com), and gained experience using a
3D printer. Additionally, the teacher wanted students
designing in authentic contexts and for authentic audiences.
They designed products for children at a local hospital,
ornaments for the White House holiday tree, and other
audiences.
In earlier work [9], we described students’ perceptions of
the engineering and science classes (taken simultaneously
and with the same teacher). The students perceived the
instruction in the engineering class as allowing for
experimentation and learning though failure. In contrast,
they saw the science class as focused on confirmatory
experiments and a focus on doing things correctly.
A. The design challenge
The teacher collaborated with a professional stuntman
(also an enrolled student’s father) who was missing part of
his leg. This was an important characteristic for the project
task because stunt doubles with amputations can use
prosthetic body parts that break, explode, or otherwise are
destroyed for cinematic effect without harming the actor.
Students were tasked with fabricating a prosthetic bone that
the stuntman would use as a prop in a movie he was
currently working on. The finished bone was required to
look realistic and break with realistic fracturing when a
force was exerted. The final bone design was also required
to fit into a “holder/connector,” measuring 200 millimeters
in length and 30 millimeters in diameter. After the bones
were designed, printed on a 3D printer, and tested, the bone
that best fit the design constraints would be used as an
actual prop in the movie. The stuntman and make-up artists
would add artificial skin and blood to the bone for use in
the movie scene. Students worked in groups of 2-4 to
complete this digital fabrication project over the course of 6
months. Fig. 1 shows the bones being placed into the
prosthetic lower leg.
B. Research#design#and#methods
This research is part of a qualitative, descriptive, case
study [10]. A case study design is particularly well suited
for studying a phenomenon that is impossible to separate
from the context itself [11]. In this research, the bounded
case under investigation is the Creative Design and
FIG 1. Student designed bones (white objects) being placed
into the prosthetic leg for testing.
Engineering classroom throughout the prosthetic bone
fabrication project. The primary research question
addressed in this study is: What opportunities for learning
physics content were created within the context of this
engineering design project?
Data collection included classroom observations from an
ethnographic perspective [12]. Ethnography “is the art and
science of describing a group or culture” [13]. Ethnographic
field notes were collected on 20 hours of class meetings,
documenting students’ design process weekly over the
course of this six-month long digital fabrication project.
We also conducted semi-structured interviews with the
teacher at the completion of the project and 4 focus groups
(13 students). The teacher interview included questions
about her motivation, planning, and instruction. The student
focus groups included questions regarding the 3D design
experience and their use of disciplinary content knowledge.
We considered the class and the digital fabrication project
to be an activity system and used cultural historical activity
theory [14] to inform the coding of transcribed interviews
and observations. Here, we focus only on a subset of the
codes—those that identify instances where students
recognized their use of scientific concepts throughout their
design process. In the full coding scheme, physics content
knowledge was just one of the many conceptual and
physical tools that students used to design their bones.
III. FINDINGS
We discuss two findings related to the students’ learning of
physics content. The first is that this experience motivated
students to learn physics. The second is that the design task
provided opportunities for students to integrate physics
content with other disciplinary content areas. A more
through analysis of the classroom and project under
investigation can be found here, [15].
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A. Design#task#motivated#use#of#physics#content
From the students’ perspective, the final product (the
prosthetic bone), not the science content, was the explicit
focus of the unit. This was in contrast to their science class
(taken simultaneously and with the same teacher) where
units were centered on disciplinary content and organized
around chapters of a textbook. One student described how
the activity required her group to use physics content
knowledge.
Sadie: We definitely did use different ideas revolving around
science. And, like, if we hit [the bone] one way, which way
would it go. Kind of like, force and momentum. Like, if I swing
it like this, will it still continue, or will it just stop. Or, at what
point [is] the breaking factor? Like, how thin will the [bone]
need to be in order to do this? Or, is this too much structure, or
not enough? So, there were definitely some underlying ideas of
science, but not like get out a book and flip through it, and [ask]
what ideas does this revolve around?
Sadie described how her group used physics content
knowledge in order to design their bone and highlighted
that there was no requirement to “get out a book and flip
through it.” Rather, Sadie described an active process of
design and construction, where her group iterated on their
design using physics concepts such as force and
momentum.
Classroom observations confirmed that students used
knowledge of physics to inform their designs. For example,
during one class meeting, a group of students discussed
their ideas with their classroom teaching assistant (also an
expert in 3D printing design and materials).
Sydney: We discovered that the breaking point [of the bone]
needs to be off-center.
Taylor: Can we make hollow sections within the bone to help it
splinter, like bubbles?
This led to a conversation about density and a discussion
about making the holes inside the bone bigger to make the
object as a whole less dense. One student then suggested an
alternative design, asking:
Sydney: Could we design it [a separation in the bone] at a
certain angle, where half the bone just slides out and forces the
other half to move?
Ms. Wilson compared this to a hubcap, which can either be
screwed or pushed onto the car’s wheel.
Sydney: We could design smaller pieces coming off the bone
that would allow it to connect to the other piece, kind of like
Legos.
Ms. Wilson: Yeah, those connecting pieces are called keys.
Taylor: Okay, well keys.
S2: I think the sliding design might work.
This was followed by a discussion about force, and where
the initial force would come from, and how that force
would impact the other parts of the bone.
In the conversation above, the physics topics emerged
from the group’s design ideas. When one student suggested
adding, “hollow sections…like bubbles” within the bone, a
conversation followed about density and how the “bubbles”
might change the density of the design. Similarly, when the
students moved onto another design idea that involved
printing the bone in two separate pieces, but connected
through the use of extruding “keys,” the conversation
focused on forces. Through brainstorming with the class
assistant, the students were able to refine their ideas over
time, using physics content knowledge, not because they
were assigned to do so, but because it helped them improve
their design. See Figure 2 for an image of this interaction.
FIG. 2 Ms. Wilson and the students discussing the ideas
of density and force to complete the bone design.#
B. Physics#content#was#integrated#with#other#areas
At the core of this project was students’ developing
understanding of forces and stresses. But, by engaging in
engineering design, physics content was not isolated from
other content areas.
Students used engineering design by iteratively creating
prototypes to ensure their product was meeting pre-
determined constraints. For example, one of the constraints
of the project was that the bone splintered when it broke.
This was to produce the desired effect for the movie. One
group observed another group test their bone and saw that it
broke evenly instead of splintering. This led them to iterate
on their design and place a hollow jagged structure inside
the bone, allowing the bone to break evenly, yet appear
jagged.
Mathematics was also embedded in the design process.
Students converted between inches and millimeters, as well
as used their knowledge of angles and proportions to create
their designs. For example the group discussed earlier
(shown in Fig. 2) refined their initial design using
knowledge of triangles, while another group of students
used algebra to calculate the different lengths of each
protruding “key” so that the two pieces could connect
seamlessly (design shown in Fig. 3).
Students also integrated physics knowledge with other
science knowledge to create a bone that looked realistic and
would fracture in a realistic manner when an outside force
was applied. To do so, students drew from their
understanding of anatomy. One pair of students noted this
in the focus group when asked if they used science content
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knowledge while designing. They described comparing
their designed bones to real bones. Additionally, students
depended upon their understanding of force, pressure, and
density to create a realistic final product, as previously
discussed.
Finally, technology was an integral part of this project.
Students created their designs using TinkerCAD
(https://www.tinkercad.com)—free, publically accessible
design software that functions within an Internet browser
and on iPads (see Figure 3)—and then printed their designs
using a 3D printer.
FIG 3. TinkerCAD design software, showing early
prototype bone designs by one group of students.
IV. DISCUSSION
With the adoption of the Next Generation Science
Standards, K-12 schools will begin to integrate engineering
design in their courses, both as a new content area and as a
way to build students understanding of physics, biology,
chemistry and earth science content. It is possible for this
change to broaden participation in physics and other STEM
areas by helping students to see physics as an essential
component to solving practical problems.
This change in K-12 schooling may also impact students’
understanding of physics and the types of physics ideas
they hold when entering post-secondary education. It is
critical that we investigate how students are interacting with
physics in engineering design tasks and the type of content
knowledge they are developing.
This study was a first step. Our goal was to describe
whether and how a group of middle school students
identified the physics in the project they were working on.
We observed that in the design task, students were focused
on their artifact (a prosthetic bone) and its intended use (a
movie prop). The focus on making their bone behave in
ways consistent with the design goals motivated them to
consider forces, density, pressure and the physics of
materials. Moreover, they considered these topics along
with mathematics and anatomy, and in the context of
participating in an iterative engineering design cycle using
technology.
We were limited in that we studied one group of students
involved in one engineering project and with a teacher who
simultaneously worked with the same set of students in a
more traditional science class. This is an ideal circumstance
and, as such, our findings are not generalizable. Instead
they describe what is possible in a best case scenario. To
effectively design engineering tasks that are both engaging
to students and help students develop physics content
knowledge and to prepare teachers to facilitate such
activities will require careful consideration and additional
research.!
ACKNOWLEDGEMENTS
The authors wish to thank the students and teachers who
generously allowed us into their classroom to complete this
research.
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