Bridging the silos: Opening a connection between physics and biology instruction

Bridging the silos: Opening a Connection

Between Physics and Biology Instruction

Edward (Joe) Redish University of Maryland 6/21/14

BioQuest 2014 1

Building a physics course for biology majors: Some questions

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  Is it possible for a physics course for bio majors to “fit in”?  Can it articulate effectively with the biology, chemistry, and math that bio students take?  How do disciplinary differences effect what and how we ought to teach?  What do we learn about these issues from Discipline-Based Education Research?

Outline

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  Context: NEXUS/Physics:   Content: Fitting into the Curriculum   Cognition: The Resources Framework

 Concepts: KiP  Epistemology

  Culture: The communication divide   Implication for Instruction: Teaching physics standing on your head

NEXUS/Physics

Context

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BioQuest 2014

In the summer of 2010, HHMI offered four universities the opportunity to:

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Develop prototype materials for biologists and pre-meds in

  Chemistry (Purdue)   Math (UMBC)   Physics (UMCP)   Capstone case study course (U of Miami)

that would  take an interdisciplinary perspective

 be competency based 6/21/14 BioQuest 2014

Change the goals of the course

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  Traditional physics is “just physics”: it ignores the needs and interests of bio students.   We want to serve biology students and faculty by articulating with the biology curriculum

 Provide support for difficult physics concepts that they will encounter in bio and chem classes.

  Use methods common in intro physics  Use simplified models to build understanding,  Build a sense of physical mechanism,  Develop coherences between things that initially seem contradictory, etc.

Changing the culture of the course

  Seek content and examples that have authentic value for the biology curriculum.

 Students should see the course as helping them understand things are important for learning biology.  Faculty teaching upper division biology (and chemistry) should want physics as a pre-requisite.

  Assume this is a 2nd year college course.  Biology, chemistry, and calculus are pre-requisites.

  Use interactive engagement pedagogy.

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Redish et al., Am. J. Phys 82:5 (2014) 368-377

The NEXUS/Physics timeline: Iterative research based design

  2010-11   Extensive discussion and negotiation among stakeholders.

  2011-12   Create on-line reading materials, problems   Teach a small test class (N ~ 20)

  2012-13   Refine and expand materials   Team teach two small flipped classes (N ~ 20)   Create new laboratories

  2013-14   Becomes the required course for all bio majors.   Fall: Deliver in two large lectures (N ~ 120): instructors from the design team.

  Spring: Teach both section in 4 large lectures with 4 new instructions.

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Detailed research on student responses – observation, interviews, surveys

Fitting with the biology curriculum

Content

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Interdisciplinarity: Rethink the content from the ground up

  Choose content that articulates with required introductory biology and chemistry classes.   Cover physics that helps students develop insight into important biological ideas.   Suppress traditional content of little value.   But ... This is a course in which students are expected to learn the physics – and see how it can be of value to biology. It is NOT “physics add-ons for biologists.”

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New interdisciplinary topics

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  Focus on modeling and explicating assumptions.   Do micro and macro examples throughout assuming students know about atoms.   Include discussion of chemical energy and reactions   Treat random motion as well as coherent. (Labs!)   Carefully build the basic statistical mechanics support for thermodynamics (conceptually).   Expand treatment of fluids and physics in fluids.

Dreyfus et al., Am. J. Phys 82:5 (2014) 403-411 Geller et al., Am. J. Phys 82:5 (2014) 394-402 Moore et al., Am. J. Phys 82:5 (2014) 387-393

Example: Chemical bonding – A bridge through 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 that can feel contradictory to them and 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.

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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 infer 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."

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From student responses we learned a useful perspective on multi-disciplinary reconciliation.

Gregor: I put that when the bond's broken it releases energy. Even though I know... that obviously that's not an energy-releasing mechanism. ...you always need to put energy in, even if it’s like a really small amount of energy to break a bond. Yeah, but like. I guess that's the difference between like how a biologist is trained to think, in like a larger context and how physicists just focus on sort of one little thing....I answered that it releases energy, but it releases energy because when an interaction with other molecules, like water...and then it creates like an inorganic phosphate molecule that has a lot of resonance. And is much more stable than the original ATP molecule. So like, in the end releases a lot of energy, but it does require like a really small input of energy to break

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B. Dreyfus, et al., “Students' reasoning about 'high-energy bonds' and ATP: A Vision of Interdisciplinary Education” Phys. Rev. ST-PER 10 (2014) 010115.

Distinct disciplinary perspectives

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  Gregor is right! Physicists and biologists (and chemists) make different tacit assumptions.   Physicists tend to isolate to focus on a particular physical phenomenon and mechanism.   Biologists (and chemists, sometimes) tend to assume the natural and universal context of life – a fluid environment (air and water taken for granted).

Approach

1.  Introduce atoms and molecules early in the class, with quantification and estimation to build a sense of scale.

2.  Introduce concept of “binding energy” in standard macroscopic energy contexts (skateboarder in a dip)

3.  Create a chain of tasks in atomic and macroscopic contexts for learning to read and interpret potential energy graphs.

4.  Refine tasks by observation of student responses and negotiation among physicists, biologists, and chemists.

5.  Be explicit about the value of different disciplinary perspectives, bridging the different two perspectives.

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6/21/14 BioQuest 2014 B. Dreyfus, et al., “Chemical energy in an introductory physics course for the life sciences”, Am. J. Phys. (May 2014).

Midterm 17

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Two students discussing the process of ATP hydrolysis (ATP + H2O ADP + Pi) make the following comments: Justin: “The O-P bond in ATP is called a ‘high-energy bond’ because the energy released when ATP is hydrolyzed is large. That released energy can be used to do useful things in the body that require energy, like making a muscle contract.” Kim: “I thought chemical bonds like the O-P bond in ATP could be modeled by a potential energy curve like this, where r is the distance between the O and the P. If that’s the case, then breaking the O-P bond in ATP would require me to input energy. I might not have to input much energy to break it, if that O-P happens to be a weak bond, but shouldn’t I have to input at least some energy?” How did Kim infer from the PE graph that breaking the O-P bond requires an input of energy? Who’s right? Or can you reconcile their statements?

The Resources Framework

Cognition

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BioQuest 2014

Key cognitive foothold ideas

1.  People have a huge store of long-term memories

2.  Items in memory are associated and can activate or inhibit each other.

3. Memory is reconstructive and dynamic. 4. Working memory is limited. 5.  Access to long-term memory

is controlled by executive function.

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Redish & Smith, J. of Eng. Educ 97 (2008) 295-307

The Resources Framework: A multi-level structure

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  Concept knowledge (basic knowledge)  Compilation and chunking  Knowledge organization (associations)

  Knowledge about when to use knowledge (switching mechanisms or control structures)

  Cultural knowledge   Framing   Epistemology

  Affect (emotional response)  Feelings (fear, self confidence, aesthetics)  Motivation   Identity

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Level 1: Knowledge in Pieces: Concepts based on embodied experience

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  Phenomenological primitives (observed)   Reasoning primitives (descriptive/inferred)   Associational patterns

Redish, Fermi Summer School CLVI (2003) Sabella & Redish, Am. J. Phys. 75 (2007) 1017-1029

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Example: Why do we have seasons?

  Essentially every elementary school student in the USA has been given the explanation.

  Then why do Harvard graduates give the wrong answer when asked?

R-Prim: Closer is stronger / more effective (neither right nor wrong) P-prim: You can get warmer by standing closer to the fire.(right) Associational p-prim: It’s warmer in the summer, so we must be closer to the source of the heat.(wrong)

A Private Universe, http://www.learner.org/resources/series28.html

Level 2: Switching mechanisms: Framing and epistemology

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  The limitations of working memory make social knowledge and perception of the learning environment critical. “Of all that I know, what should I use right now?”   Framing

 Answers the question: “What’s going on here?” (calling on experience and expectations)

  Epistemology  The study of answering the questions: “What’s the nature of the knowledge we are learning?” and “What are we supposed to do in order to learn it?”

Structures and concepts useful for analyzing epistemological issues

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  Warrants   Specific statements explaining why a particular claim is true using specific reasoning.

  Epistemological resources (e-resources)  Generalized categories of “How do we know?” warrants.

  Epistemological framing   The process of deciding what e-resources are relevant to the current task. (NOT necessarily a conscious process.)

  Epistemological stances  A coherent set of e-resources commonly activated together in a particular circumstance

Bing & Redish, Phys. Rev. ST-PER 5 (2009) 020108; Phys. Rev. ST-PER 8 (2012) 010105. Tuminaro & Redish, Phys. Rev. ST-PER 3 (2007) 020101.

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 Can a fine-grained analysis of disciplinary-specific epistemological resources, framing, and stances help us create better instructional environments and practices in physics for biology students?

The Communication Divide

Culture

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BioQuest 2014

Disciplinary expectations leads to epistemological framing

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  Students choose a field, in part, because they have some expectations about what it does and how it functions.   In becoming disciplinary experts, students learn the methods and ways of thinking of their discipline.   These two sets of understandings do not necessarily match, nor match with those of their (outside of discipline) instructors in service courses.

Epistemological resources

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Knowledgeconstructed

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 regularityand reliability and are

consistent across different situations.

Highly simplified examples can yield

insight into complex mathematical

representations

IntroPhysicscontext

Epistemological resources (short names)

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is trustworthy

Algorithmic computational steps lead to a trustable

result



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 regularityand reliability and are

consistent across different situations.

Highly simplified examples can yield

insight into complex mathematical

representations

Physical intuition (experience & perception)

Calculationcan 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

IntroPhysicscontext

Example:

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  An engineering student is asked about something he hasn’t studied yet: pressure under water.   His intuition is that the pressure increases as you go deeper.   But when he’s given the equation: he gets a sign wrong and concludes the pressure must decrease as you go deeper.

p = p0 + ρgh

Gupta & Elby , Int. J. Sci. Ed 33:18 (2011) 2463-2488

Epistemology is dynamic and responds to a variety of expectations.

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Analyzing the framing shift of an engineering student to a physics problem he had not seen before.

•  Coordinated math and intuition

•  Positive affect

IntroBiologycontext

Epistemological resources

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is trustworthy



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

There are broad principles that govern

multiple situations

Living organisms are complex and require multiple

related processes to maintain life

IntroBiologycontext

Epistemological resources (short names)

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is trustworthy





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 situationsHeuristics

Living organisms are complex and require multiple

related processes to maintain life

Life is complex(system thinking)

Note:

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  These groupings of resources are labeled as “Intro Bio” and “Intro Physics.”   This is to indicate that these are epistemological resources commonly perceived by students as relevant in their intro classes in these subjects.   Professionals in both fields tend to use both of these sets resources (though with different distributions and depending on sub-field).

Some examples from Bio

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  Biology III: Organismal Biology  A principles-based class that structures the traditional “forced march through the phyla” of a biological diversity class.

  Some of the principles:  Common ancestry (deep molecular homology)  Individual evolved historical path) (divergent structure-function relationships)  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

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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

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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.

Watkins & Elby, CBE-LSE 12 (2013) 274-286.

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.

Ashley’s dynamic switch

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“Biological authenticity” – •  Coordinated math and intuition •  In a biological context •  Positive affect •  Significant value for

understanding biology

Recitation task: Why do bilayers form?

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Prompt: Which term wins?

Prompt: …explain how phospholipids can spontaneously self-assemble into a lipid bilayer…why this particular shape?

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Hollis: I mean, in terms of like bio and biochem, the reason why it forms a bilayer is because polar molecules need to get from the outside to the inside ... so you need a polar environment inside the cell. But I don't know how that makes sense in terms of physics. So... Cindy: So like what I'm saying is, you have to have, like if it's hydrophobic and interacting with water, then it's going to create a positive Gibb's free energy, so it won't be spontaneous. So, in this case, you have the hydrophobic tails interacting with whatever's on the inside of the cell, which is mostly water, right? Hollis: Or other polar molecules. Cindy: Yeah, other polar molecules. It's going to have, and that's bad ... That's a positive Gibb's free energy. Hollis: Yes. See, you explained it perfectly ... Cause I was thinking that, but I wasn't thinking it in terms of physics. And you said it in terms of physics, so, it matched with bio.

Disciplinary epistemologies

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  “in terms of bio, the reason why it forms a bilayer is because polar molecules need to get from the outside to the inside”   “ if it’s hydrophobic and interacting with water, then it's going to create a positive Gibb's free energy, so it won't be spontaneous and that’s bad..”

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IntroBiologycontext



Satisfaction(smile,

fist pump)

Interdisciplinary coherence

seeking

“Interdisciplinary coherence” – •  Coordinated resources from

intro physics and biology •  Blended context •  Positive affect

Teaching Physics standing on your head

Implications for Instruction

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BioQuest 2014

Does such an analysis help?

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  An epistemological analysis provides a finer-grained approach to understanding student responses to instruction.   That might help us to better understand interdisciplinary communication and to helping us design more effective instructional environments.

What’s wrong with physics teaching? The “go-to” e-resource

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 The epistemological stances naturally taken by physics instructors and biology students may be dramatically different – even in the context of a physics class.  One example from my observations of other faculty teaching NEXUS/Physics yields an insight.

The figure shows the PE of two interacting atoms as a function of their relative separation Is the force between the atoms at the separations marked A,B, and C attractive, repulsive, or zero?

C

B A Total energy

r

Potential Energy

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How two different professors explained when students got stuck on this.

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  Remember! (or in 1D)   At C, the slope of the U graph is positive.   Therefore the force is negative – points to smaller r.   So the potential represents an attractive force when the atoms are at separation C.

F = −∇U F = − dU

dr

This figure was not actually drawn on the board by either instructor.

Wandering around the class while the students were considering the problem, I found a good response with a different approach.

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  A hill is a good analogy for PE   Think about it as if it were a ball on a hill. Which way would it roll? Why?   What’s the slope at that point?   What’s the force?   How does this relate to the equation

F = − dU

dr

A conflict between the epistemological stances of instructor and student make things more difficult.

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Calculationcan be trusted


Physical mapping

to math(Thinking with math)




Mathematical consistency

(If the math is the same, the analogy is good.)

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 blending math and conceptual knowledge, so they are more comfortable beginning with physical intuitions.

Teaching physics standing on your head

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  For physicists, math is the “go to” epistemological resource – the one activated first and the one brought in to support intuitions and results developed in other ways.   For biology students, the math is decidedly secondary. Teleology (structure/function) tends to be their “go to” resource.   Part of our goal in teaching physics to second year biologists is to improve their understanding of the potential value of mathematical modeling. This means teaching it rather than assuming it.

So does it work? One student mulls on making sense of force and energy in enzymatic reactions.

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I mean cause, you get this equation in chemistry and biology and now in this class. But you learn it from all different ways, all different angles. And I feel like in this class it’s so much combined with biology you have to put those two realms together...[I: And this is an example of opposite or coming together?] Coming together. Definitely. Cause like in bio you’re always like, “Oh, delta G is how much free energy you have to do work in the system.” And now in this class you actually have a specific definition of what work actually is. Instead of just like, “Oh, it can make this product,” but you can see that, like, how an enzyme fits into what work is. ΔG = ΔH −TΔS

ΔH = ΔU + pΔV

What you need to do multidisciplinary instructional development

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  Understand that disciplines take different perspectives on the world – for good reasons.   Respect what each discipline brings to the table.   Respect students’ disciplinary perceptions of themselves and the knowledge and perspectives they bring to each class.   Create stable and longstanding conversations with your colleagues in other disciplines!

Redish & Cooke, “Learning each other’s ropes,” CBE-LSE 12 (Summer2013) 175-186