Can We Talk? The challenge of cross-disciplinary STEM instruction

Can we talk?
The challenge of cross-disciplinary
STEM instruction and communication
E. F. (Joe) Redish
University of Maryland
Department of Physics
11/1/18 Bennhold Lecture, GWU

Cornelius Bennhold ( 1960- 2009)
11/1/18 Bennhold Lecture, GWU 2

STEM Education: Who teaches whom?
• We care about our majors.
(Of course! They are future us.)
A lot of our instructional effort focuses on them.
• We not only teach our own majors.
STEM supports STEM
• “Service courses” represent a large fraction
of students being taught in many STEM departments.
o Physicists teach engineers.
o Chemists teach biologists.
o Mathematicians teach us all.

In Physics, a growing fraction of our
service students are from the life sciences
• Life science is the fastest growing STEM field.
• The total number of life science degrees granted
is greater than the number of engineering degrees.*
• We have traditionally taught life science students
as “other” – in our catchall class that included
non-STEM majors.
• Many life science students tend to be
”turned off” by physics, are afraid of it,
and some are explicitly hostile.
* National Science Board, Science and Engineering Indicators (2018).

This presents an interesting
opportunity for research!
• Life science students tend to be happy
with chemistry. Why do they reject physics?
• These students are going to be our doctors, nurses,
and health-care givers. Shouldn’t we do whatever
we can to help them be better scientists?
• The life sciences have been growing spectacularly
in the last few decades, becoming recognizably
more scientific (to a physicist) and more technical.

Furthermore, biologists
are clamoring for an upgrade
• Leading research biologists
and medical professionals
have increasingly been calling
for a major reform
of undergraduate instruction.
• They want more development
of scientific skills
and more multi-disciplinarity.

A personal trajectory
• My department first asked me to teach
algebra-based physics with the pre-meds in 1975.
• In 1992 I turned my research efforts from
Nuclear Theory to Physics Education Research.
• Between 2000 and 2009 I did extensive research
on student learning in the algebra-based physics class
with emphasis on scientific skill development.
• In 2006 I began a close interaction with a biologist
and worked with him on adding active engagement
to his class in biological diversity.

NEXUS/Physics
• In 2010, building on work that our work
in algebra-based physics and biology,
we were given a challenge grant from HHMI.
• Our charge was to reform the physics class
for life science students as part of a national effort
to increase their skill development
and multi-disciplinary strengths. (National Experiment
in Undergraduate Science Education – NEXUS).
E. F. Redish, et al. (17!) Am. J. Phys. 82:5 (2014) 368-377. doi: 10.1119/1.4870386

Deep research
• We brought together a large team of physicists,
biologists, chemists, curriculum developers,
and education researchers.
• We spent a year discussing what physics could do
as part of a biology program for biologists
and pre-health care students.
• We spent two years teaching the class in small classes,
videotaping everything in sight and learning as much as
we could from listening to (and interviewing) the students.

We learned some things that surprised us
• There were serious issues of disciplinary culture
and communication that we had not expected.
• Maybe we should have, since teaching
is all about communicating, and I know the key
to teaching is to learn to listen to students.
• But did I also have to learn to listen
to my colleagues in biology, chemistry, and math?
We’re all scientists, after all.

Sense-making and meaning
• In teaching physics, I want my students
to not only learn facts and procedures;
I want them to make sense of the physics,
— to understand what physics means.
• For life science population in particular,
I want them to learn to make meaning
with math.

The meaning of meaning
Communication and culture

How do we know what we mean?
• We communicate through language,
but what matters is not just the words.
We make meaning through associations
to a rich set of knowledge that we bring
from extensive experience.
• Language is both phrased and interpreted
through the individual’s social and physical
knowledge and on their interpretation
of their situation: culture and context.

Culture: What we use to interpret context
• Culture is what we learn from experience
that lets us make sense of context.
• Culture belongs to individuals and depends on
experience with social groups and situations
— family, peers, school, media, language.
• These factors strongly affect how we interpret
and interact with the world and people around us.
• Individuals can have multiple cultures that they
activate under different circumstances.
* Michael Agar, Language Shock: Understanding the Culture of Conversation (Perennial, 1994)

Communication successes and failures
• We understand others
through our common experience and humanity.
• We misunderstand others
when we are unaware of our cultural differences.
• When we communicate, we are always translating,
inferring the speaker’s meaning.
• But our associations and interpretations are cultural
and depend on our own perception of the context.
• If others bring a different culture or interpretation
of the context than we do, we can have serious confusion.

Two ways of looking at differences
between you and someone else
1. Notice all the other things that the other
person lacks when compared to you,
the deficit theory approach.
2. Figure out that the differences are
the tip of the iceberg, the signal
that two different cultural systems
are at work.

Rich points
• When we find an unexplained difficulty
— a rich point — we need to understand it
as two distinct cultures reaching for each other.
We have to put our own culture and assumptions
under scrutiny as well as the one we are observing.
• “The rich points in a languaculture you encounter are
relative to the one you brought with you.... If you hit a
rich point, think you’ve solved it, and haven’t changed
[yourself], then you haven’t got it right.” (Agar)

Rich point 1:
The biologists way of looking at math

An interview with a Bio student
• Context: Biology III: Organismal Biology
o A principles-based class that re-structures
the traditional “forced march through
the phyla” of a biological diversity class.
• Some of the principles:
o Common ancestry (deep molecular homology)
o Individual evolved historical path
(divergent structure-function relationships)
o Biology is constrained by universal
chemical and physical laws.
• Uses Group Active Engagement (GAE) lessons
(including math!)
“Todd the biologist”

Ashley’s response
to the use of math in Org Bio
Discussing the use of Fick’s Law
in controlling diffusion through
a membrane of different thicknesses.
I don’t like to think of biology in terms of numbers
and variables…. biology is supposed to be tangible, perceivable, and
to put it in terms of letters and variables is just very unappealing to
me…. Come time for the exam, obviously I’m going to look at those
equations and figure them out and memorize them, but I just really
don’t like them.
I think of it as it would happen in real life. Like if you had a thick
membrane and tried to put something through it, the thicker it is,
obviously the slower it’s going to go through. But if you want me to
think of it as “this is x and that’s D and this is t”, I can’t do it.
x2
= 2Dt

Another response of a student
to math in Org Bio
The small wooden horse supported on dowels stands
with no trouble. When all dimensions are doubled,
however, the larger dowels break, unable to support
the weight.
The little one and the big one, I never actually
fully understood why that was. I mean, I
remember watching a Bill Nye episode about
that, like they built a big model of an ant and it
couldn’t even stand. But, I mean, visually I knew
that it doesn’t work when you make little things
big, but I never had anyone explain to me that
there’s a mathematical relationship between that, and that
was really helpful to just my general understanding of the
world. It was, like, mind-boggling.
Watkins & Elby, CBE-LSE 12 (2013) 274-286.
The same student!

Biology students value authenticity
• Biology students valued math much more
when it had implications for biological insights
they personally viewed as valuable.
• Showing that “physics could be applied
to biological organisms” was consistently treated
as a “so what” if it did not offer biological insight.
• What about faculty?
J. Watkins, J. Coffey, E. Redish, & T. Cooke, Phys Rev ST Phys Educ Res 8 (2012) 010112.

Starting NEXUS/Physics for real
• For our first week of NEXUS/Physics,
I asked Todd to provide me a problem on scaling
(surface and volume effects) for a discussion
of measurement and functional dependence.
• He came up with a great problem about worms.
It looked like this:

A problem posed
by a biologist for a bio class
A typical earthworm has the following dimensions:
weight = 3.7 g, length = 12 cm, width = 0.64 cm.
Oxygen consumption of the body = 0.98 μmole O2/g
Oxygen absorption across the skin = 2.4 nmole O2/mm2.
Model the shape of the worm as a solid cylinder. For the worm above,
calculate its surface area (ignore the blunt ends), volume, and density.
Worms absorb oxygen through their skin, so proportional to their area, but almost all of the cells in
their body use oxygen in respiration, proportional to their volume. Assuming the rates above, show
whether or not the typical worm can absorb sufficient oxygen to maintain the respiratory rate of its
entire body.
Organisms can grow in two ways: by increasing its length, keeping other dimensions the same, or
isometrically -- by increasing all of its dimensions by the same factor. Calculate whether a worm that
doubles a length can survive and whether a worm that doubles isometrically can survive.
Dave Coverly: Speed Bump
(with permission)

Added by a physicist
for a physics class
Consider a general cylindrical organism of density d, length L, and radius R.
If the rate of oxygen absorption through the skin is A, and the rate it uses
oxygen in the volume is B, write a symbolic expression for the total rate
of oxygen used by the worm. Find the maximum radius the worm could be
before it would have a problem taking in enough oxygen.
Rate oxygen is absorbed = 𝐴𝑆 = 𝐴(2𝜋𝑅𝐿)
Rate oxygen is used = 𝐵𝑑𝑉 = 𝐵 𝑑 𝜋𝑅2 𝐿
Condition for survival: 𝐴𝑆 > 𝐵𝑑𝑉
2𝜋𝑅𝐿𝐴 > 𝜋𝑅2 𝐿𝐵𝑑 2𝐴
𝐵𝑑
> 𝑅
Dave Coverly: Speed Bump
(with permission)

The reaction of the development team
to my suggested changes surprised me.
• The physicists around the table to a person,
responded, “Oooh! Neat!” 👍
• The biologists around the table
reacted differently.
• They said, “Yuck! You’ve removed the biology!
That’s not the way worms grow. The radius
never grows by itself.” 👎

The compromise: Add this
• Our analysis was a modeling analysis. An earthworm
might grow in two ways: by just getting longer or by scaling up
in all dimensions. What can you say about the growth of
a worm by these two methods?
• In typical analyses of evolution and phylogenetic histories,
earthworm-like organisms are the ancestors of much larger
organisms than the limit here permits. What sort of variations
in the structure of a worm-like ancestor might lead to an
organism that solves the problem of growing isometrically
larger than the limit provided by the simple model?

Understanding biologists
– and ourselves as physicists as well
• Biologists, both students and faculty, value
real world examples. Numbers make
the connection between math and reality.
• Physicists, on the other hand, value abstractions,
simplifications, and universal mathematical
principles.
• We analyzed the differences we saw as
epistemological resources (ways of knowing).
11/1/18 Bennhold Lecture, GWU 28E. F. Redish and T. J. Cooke, CBE-LSR, 12 (June 3, 2013) 175-186. doi:10.1187/cbe.12-09-0147.

Epistemological resources
(Discipline of physics)
Knowledge
constructed
from experience
and perception (p-prims)
is trustworthy
Algorithmic
computational steps
lead to a trustable
result
Information from
an authoritative
source
can be trusted
A mathematical symbolic
representation faithfully
characterizes some feature
of the physical or geometric
system it is intended
to represent.
Mathematics and
mathematical manipulations
have a regularity
and reliability and are
consistent across different
situations.
Highly simplified
examples can yield
insight into complex
mathematical
representations
Physical intuition
(experience & perception)
Calculation
can be trusted
By trusted
authority
Physical mapping
to math
(Thinking with math)
Mathematical
consistency
(If the math is the same,
the analogy is good.)
Value of
toy models
Intro
Physics
context

Intro
Biology
context
Epistemological resources
(Discipline of biology)
11/1/18
Bennhold Lecture, GWU 30
Knowledge
constructed
from experience
and perception (p-prims)
is trustworthy
Physical intuition
Information from
an authoritative
source
can be trusted
By trusted
authority
The historical fact of
natural selection leads
to strong structure-
function relationships
in living organisms
Many distinct
components of
organisms need to be
identiﬁed
Comparison of related
organisms yields
insight
Learning a
large vocabulary
is useful
Categorization
and classiﬁcation
(phylogeny)
There are broad
principles that govern
multiple situations
Heuristics
Living organisms
are complex and
require multiple
related processes to
maintain life
Life is complex
(system thinking)

How biologists see physicists
Randall Munroe: xkcd

How physicists see biologists
• A biophysicist friend was working with a group
of biologists to study single molecular interactions
of important reactions that occur in cells.
• The physicist wanted to do the experiment
on clean glass in a vacuum.
• He said the biologists wanted to do
the experiment “inside a dog.”

One cross-disciplinary failure
of teaching physics to biologists:
The “go-to” e-resource
• The epistemological stances
naturally taken by physics instructors
and biology students
may be dramatically different –
even in the context of a physics class.

A conflict between
the epistemological stances of instructor
and student make things more difficult.
11/1/18
Bennhold Lecture, GWU 34
Physical intuition
Physical mapping
to math
Mathematical
consistency
(If the math is the same,
the analogy is good.)
Calculation
can be trusted
By trusted
authority
Physical mapping
to math
Physics instructors
seem more
comfortable
beginning with
familiar equations
– which we use
not only
to calculate with,
but to code
and remind us
of conceptual
knowledge.
Most biology students
lack the experience
of blending math and
conceptual knowledge,
so they are more
comfortable
beginning with
physical intuitions.

Instructional implication
• It may be better for a physics teacher
to “teach physics standing on your head”,
running the epistemological chain backwards
from the way that feels most natural to us.
• (And maybe this is even true
for our own novice majors.)

Rich point 2:
The source of chemical energy

The energetics of chemical bonding
– Interdisciplinary reconciliation
• In introductory chemistry and biology classes,
students learn about chemical reactions
and the critical role of energy made available
by molecular rearrangements.
• But students learn heuristics by rote
and that can feel contradictory to them in a way
that they often don’t know how to reconcile.
1. It takes energy to break a chemical bond.
2. Breaking the bond in ATP is the “energy currency”
providing energy for cellular metabolism.
W. C. Galley, J. Chem. Ed., 81:4 (2004) 523-525.
M. Cooper and M. Klymkowsky, CBE Life Sci Educ 12:2 (2013) 306-312

Many students bring a “piñata” model
of a chemical bond.
"But like the way that I was thinking of it, I don't know why,
but whenever chemistry taught us like exothermic, endothermic,
like what she said, I always imagined
like the breaking of the bonds
has like these little [energy]
molecules that float out,
but like I know it’s wrong.
But that's just how
I pictured it
from the beginning."

Huh! If it takes energy to break
a chemical bond, where DOES
the energy come from?
(Like we get from food)
Isn’t it chemical energy?

Here’s a classical model. (The Gauss Gun)
Watch it on you tube at (or check out any other version – many are available
https://www.youtube.com/watch?v=fiSd91sLtS4

Here’s how it works:
The energy comes from potential energy!

Distinct disciplinary perspectives
• Physicists and biologists (and chemists)
make different tacit assumptions.
• Physicists tend to isolate a system to focus
on a particular physical phenomenon
and mechanism.
• Biologists (and chemists) tend to assume the
natural and universal context of life – a fluid
environment (air and water taken for granted).
Sources of energy
in biological systems:
Glucose and ATP

• We learned to not try to condemn
one or the other perspective as “wrong”
but to be explicit and discuss
the different ways different disciplines
look at the same phenomenon – and why.

To set up an instructional path
to clarify this, let’s analyze
how meaning is made
in abstract situations
using some tools from
cognitive linguistics
and semantics.
G. Lakoff and M. Johnson, Metaphors We Live By (U, if Chicago, 1980/2003)
G. Fauconnier and M. Turner, The Way We Think (Basic Books, 2003)

Building up abstract concepts
• According to L&J and F&T, we build up
abstract and complex concepts by beginning with
concrete knowledge gained from direct experience,
and using metaphors that gain meanings
of their own to create new mental models.
• We then blend different mental models
to create even more complex ideas.
• Often, in physics, we deal with constructed
quantities that do not match directly
with everyday experience. We use blending.

Ontological metaphors for energy: 1
Energy as a substance
Scherr et al. 2012
Energy is in objects
Objects have energy
science.howstuffworks.com
B. W. Dreyfus, et al., Phys. Rev, ST-PER 10 (2014) 020108

Energy as a vertical location
phet.colorado.edu
Objects are at energies
Objects go to higher/lower energy
Ground state
Excited states
Ontological metaphors for energy: 2

Experts blend these metaphors seamlessly,
building a new, more complex description.
Adding a photon (”stuff”), excites
the molecule to an excited
(“higher”) energy state.

Can our understanding of the details
of what we usually take for granted help?
• Build a coherent story using toy models
o Bulldog on a skateboard
o Atomic interactions
and binding
o Reactions in which bonds
are first broken and then
stronger ones formed
(the Gauss gun)
o Biological examples that
give authentic insights
(photosynthesis).

A series of clicker questions (PhET based)
helps students get comfortable with negative PE
and with the concept of binding energy.
Same problems analyzed
with shifted zero of PE –
one positive E, one bound.

Bound states
HW problem
The skateboarder is just
an analogy for the cases
we are interested in --
interacting atoms.
If the atoms have an energy
of -7.5 units as shown
by the solid line in the figure,
would you have to put in
energy to separate the atoms
or by separating them would
you gain energy? How much?
Explain why you think so.

Student drawing from a HW
on the reaction H2 + O2  2H2O

Chemical Energy Thread affects the entire course
11/1/18 Bennhold Lecture, GWU 55Dreyfus et al., Am. J. Phys 82:5 (2014) 403-411

Some student comments
• “At first I was expecting the class to be like the biology calculus
class that did not focus on any biology. But, as the semester
progressed, I saw that the class was actually directed towards
helping students to understand biological ideas using physics. “
• “…[biology professors] have to go over so much stuff that they
don't really take the time to go over why things happen. And I'm a
very why kind of person. I want to understand why does this
happen? ...And you know [diffusion] was never explained to me
very well, and then when I take this [physics] class and understand
oh well this is why molecules interact the way they do.“
• “I now see that physics really is everywhere, and the principles of
physics are used to govern how organisms are built and how they
function.”

Take away message
• There are significant cultural differences between how
a physics instructor frames an introductory physics class
and how a life sciences major frames the same class,
especially the role of mathematics and epistemology.
• Physics instructors are strongly tempted to treat
these differences with a deficit theory that leads
to more confusion and student resistance.
• Only by treating research into these issues as an interaction
between two distinct cultures — the student’s and
the instructor’s — can we make sense of what’s going on.

Multi-disciplinary vs inter-disciplinary
• We encountered many rich points in our
exploration of the interaction between
the cultures of physics and biology.
• We not only learned to respect biology
as a scientific discipline with a scientific culture
distinct from the culture of physics —
we learned a lot about how we
as physicists do physics that we
had not previously understood!

The NEXUS/Physics “Gang of 5”
Left to right:
Ben Geller
Vashti Sawtelle
Chandra Turpen
Julia Gouvea
Joe Redish
Ben Dreyfus

The NEXUS Development Team (UMCP)
 Physicists
• Joe Redish
• Wolfgang Losert**
• Chandra Turpen
• Vashti Sawtelle
• Ben Dreyfus*
• Ben Geller*
• Kimberly Moore*
• John Gianini* **
• Arnaldo Vaz (Brazil)
 Biologists
• Todd Cooke
• Karen Carleton
• Joelle Presson
• Kaci Thompson
 Education (Bio)
• Julia Svoboda Gouvea
• Gili Marbach-Ad
• Kristi Hall-Berk*
* Graduate student
** Biophysicist

Discussants:
UMCP co-conspirators
 Physicists
• Arpita Upadhyaya**
• Michael Fisher
• Alex Morozov**
• Peter Shawhan
 Biologists
• Marco Colombini***
• Jeff Jensen
• Richard Payne
• Patty Shields
• Sergei Sukharev**
 Chemists
• Jason Kahn***
• Lee Friedman
• Bonnie Dixon
 Education
• Andy Elby (Phys)
• Dan Levin (Bio)
• Jen Richards (Chem)
** Biophysicist
*** Biochemist

Off-campus collaborators
 Physicists
• Catherine Crouch
(Swarthmore)
• Royce Zia
(Virginia Tech)
• Mark Reeves
(George Washington)
• Lilly Cui & Eric Anderson
(UMBC)
• Dawn Meredith
(U. New Hampshire)
• Steve Durbin
(Purdue)
 Biologists
• Mike Klymkowsky
(U. Colorado)
 Chemists
• Chris Bauer
(U. New Hampshire)
• Melanie Cooper
(MSU)
 Education
• Janet Coffey
(Moore Foundation)
• Jessica Watkins
(Tufts University)

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