Challenges and successes in an interdisciplinary physics course for ...

Rounding off the cow: Challenges and successes in an interdisciplinary physics course for life science students Dawn C. Meredith and Jessica A. Bolker Citation: Am. J. Phys. 80, 913 (2012); doi: 10.1119/1.4733357 View online: http://dx.doi.org/10.1119/1.4733357 View Table of Contents: http://ajp.aapt.org/resource/1/AJPIAS/v80/i10 Published by the American Association of Physics Teachers

Related Articles Providing the Essential Questions of the Course to Students Phys. Teach. 50, 486 (2012) Could Physics Majors Disappear? Phys. Teach. 50, 328 (2012) Human Subjects Research and the Physics Classroom Phys. Teach. 50, 363 (2012) Online Prelectures: An Alternative to Textbook Reading Assignments Phys. Teach. 50, 301 (2012) Encouraging Student Participation in Large Astronomy Courses Phys. Teach. 50, 146 (2012)

Additional information on Am. J. Phys. Journal Homepage: http://ajp.aapt.org/ Journal Information: http://ajp.aapt.org/about/about_the_journal Top downloads: http://ajp.aapt.org/most_downloaded Information for Authors: http://ajp.dickinson.edu/Contributors/contGenInfo.html

Downloaded 09 Nov 2012 to 132.177.90.107. Redistribution subject to AAPT license or copyright; see http://ajp.aapt.org/authors/copyright_permission

Rounding off the cow: Challenges and successes in an interdisciplinary physics course for life science students Dawn C. Mereditha) Department of Physics, University of New Hampshire, Durham, New Hampshire 03824

Jessica A. Bolker Department of Biological Sciences, University of New Hampshire, Durham, New Hampshire 03824

(Received 19 December 2011; accepted 20 June 2012) We describe a 4-yr project designing, teaching, and assessing an interdisciplinary algebra-based physics course for undergraduate biology students. We addressed the needs of this cohort through careful selection of topics and rich biological applications, while also attending to deeper pedagogical concerns (students’ conceptual understanding, epistemological stance, and ability to connect meaning and mathematics). The course provided biology/physics connections that students value, and their work indicated an ability to understand and integrate physics in biological contexts. We offer strategies, suggestions, and some cautionary tales for faculty contemplating or already engaged in similar endeavors. VC 2012 American Association of Physics Teachers. [http://dx.doi.org/10.1119/1.4733357]

I. INTRODUCTION

•

Our title is lifted from a well-worn story: consulted about methods to increase milk production in a dairy herd, a physicist responds, “Consider a spherical cow….” The old joke captures one of the difficulties of designing a physics course that will better serve students who are more interested in real cows (as well as fish, bacteria, and humans) than in the idealized, often simplified objects and phenomena in introductory physics textbooks. This is not a new problem: it is well known that the needs of life science students differ from those of students in physical science and engineering.1 The search for solutions to this problem has received new impetus in the past decade from four national reports focused on undergraduate biology education.2–5 Bio2010: Transforming Undergraduate Education for Future Research Biologists2 describes three reasons why biology students should study physics: First, there are the specific and quantitative principles of physics on which a microscopic understanding of biology is ultimately based and on which much of the instrumentation of biological research is also based…. Second, and more abstract, physics is a more mature science with far less complexity than biology, in which a student can more easily learn about the interactive relationship between experiment, theory, modeling, and analysis. Third, much of physics is about the behavior of dynamical systems. Biologists need to understand dynamics, for biology is fundamentally a driven, dissipative system, not at equilibrium (p. 155). Scientific Foundations for Future Physicians3 lists expected competencies for students entering medical programs and proposes that defined competencies replace required courses as pre-requisites for admission; their recommendations draw directly on Bio2010. The three student competencies6 most relevant to college physics courses are the abilities to: 913

Am. J. Phys. 80 (10), October 2012

http://aapt.org/ajp

•

•

apply quantitative reasoning and appropriate mathematics to describe or explain phenomena in the natural world (p. 22); demonstrate understanding of the process of scientific inquiry and explain how scientific knowledge is discovered and validated (p. 24); demonstrate knowledge of basic physical principles and their applications to the understanding of living systems (p. 26).

The pre-health professional entrance examinations (Medical College Admissions Test [MCAT]7 and the lesser-known Optometry Admissions Test8) are long-standing external influences on introductory physics courses for life science students. Some instructors assume that preparing students for the MCAT requires teaching all the topics in a standard college physics text, likely resulting in superficial coverage. Contrary to this assumption, however, Zheng et al.9 demonstrate that a large percentage of MCAT questions require critical thinking, not just recall.10 This focus on depth rather than breadth is echoed in the recent MCAT Fifth Comprehensive Revision (MR5);4 a recommendation particularly important for physics instructors is the plan to “test examinees’ knowledge and use of the concepts…[that are] most important to entering students’ success” (emphasis added). The Vision and Change group,5 catalyzed by recent significant changes in the field of biology and the science of learning, has issued a call to action to all who teach undergraduate biologists. They recommend teaching core concepts “evolution; pathways and transformation of energy and matter; information flow, exchange, and storage; structure and function; and systems” in courses that are “active, outcome-oriented, inquiry-driven, and relevant.” These national reports have helped to focus and energize efforts within the physics community to improve the standard course in Introductory Physics for Life Science Students (IPLS) and have led to the formation of a national group of physics educators interested in the IPLS course. This group has met at AAPT meetings and at stand alone-workshops, and identified a number of common goals and concerns.11 C 2012 American Association of Physics Teachers V


913

Our own students also call for change: Please give a lot more biological examples to relate physics to something we bio majors understand! It captures our attention SO much more and gets us to understand concepts so we can do better in the class. We like animals and plants and things like that, and we want to understand these things, so if you play off our interests more it will help us do better. Physics is an interesting subject for a lot of people, but concepts are hard to grasp without making direct connections between it and other things we know and like.12 Driven by both national and local calls for change, we set out to transform a standard introductory physics course populated mainly by biology students into an explicitly interdisciplinary course designed to meet our students’ needs. This paper summarizes what we learned along the way. We begin with the local context: class format and student characteristics. We then describe how we redesigned the course and what we learned about integrating biology into a physics class. We present data about outcomes, including an overview of student perceptions of the project. Finally, we discuss unsolved problems, including the challenge of transforming a local, individual initiative into a broader institutional change. II. LOCAL CONTEXT Our IPLS course served 250–320 students each semester and was split into two lecture sections that each met three times a week. Every student also enrolled in a weekly lab section. There were no scheduled recitations or problem solving sessions; however, we provided several options for group work outside of class, facilitated by either peers13 or instructors, and sometimes used lab time for group problem solving. Most of our students were juniors or sophomores. Over 85% were from the College of Life Science and Agriculture and took the course to fulfill a major requirement. Although some planned to apply to medical school, many were interested in areas such as marine ecology, zoology, behavior, neuroscience, and microbiology. Fifteen to 20% of our students viewed the class as a good way to study for the MCAT, and 15%–30% perceived it as useful to their future careers. Independent of its perceived utility, 15%–20% saw physics as inherently fun and/or interesting. Our students’ physics and mathematics background varied widely. About 25% of our students had no previous physics instruction; 25% had taken conceptual physics, 40% had taken college preparatory physics, and 10% had taken an AP or college-level course. Although 75% had taken calculus, 18% sometimes found the algebra and trigonometry in our class too difficult. For 76% mathematics was not a barrier to learning, and 5.5% would have liked more challenging mathematics. III. COURSE DEVELOPMENT AND PEDAGOGY A. Co-teaching Our goals in the IPLS course were both to teach physics effectively and to demonstrate connections between physics and biology. In particular, we wanted students to understand 914

Am. J. Phys., Vol. 80, No. 10, October 2012

how and why physics is important within biology at levels from ecology and evolution, through organismal form and function, to instrumentation. With this motivation, we sought to test the hypothesis that a thoroughly interdisciplinary IPLS course was an effective approach to teach physics to life science students and that developing such a course would be an interesting, though difficult, venture. Our IPLS course was co-developed and co-taught over 4 yr by a physicist (D.C.M.) and a biologist (J.A.B.). We believe that close faculty-level collaboration across disciplines is the best way to run an interdisciplinary course. Such visible collaboration offers students two important benefits: the experience of working with faculty with dissimilar backgrounds, who have different training, perspectives, and approaches; and a practical model of colleagues from different disciplines actively collaborating on an integrative project. Seeing a biologist and a physicist working together to offer a genuinely interdisciplinary course sends a powerful message about the value we place on integration. B. Pedagogy Biological applications that may improve student motivation are not, by themselves, sufficient to produce effective learning in a physics class.14 Beyond working to integrate biology into the course content, we also focused on conceptual understanding15 using peer instruction16 and group problem solving on challenging questions.17 We chose the text by Knight, Jones, and Field18 as it aligned with several of our priorities: modeling, focus on concepts, and awareness of students’ initial ideas about physics. Students’ personal epistemologies (beliefs about learning and knowledge) were addressed through a focus on sensemaking and refining intuitions.19,20 Our labs were informed by Modeling Instruction (MI)21 in order to explicitly address epistemology, allowing students to engage in authentic scientific inquiry in the classroom. MI was adapted by graduate student Christopher Shubert in collaboration with Professor James Vesenka in order to accommodate our shorter class periods and novice lab instructors, and also to integrate biological topics.22 C. Choice of topics Traditional introductory physics courses acknowledge only slightly the needs of life science students. Typically the breadth of topics covered is the same as for the engineers; biologists’ interests are addressed only through biology-related examples or homework questions.23,39 But this approach fails to meet their real needs—few topics have equal value to engineers and to biologists. Treating the IPLS class as a minor variation on the engineering course is like pouring salsa over a meatloaf and then declaring it a Mexican dish. We took a different approach, deliberately choosing topics with our biology students’ needs and interests in mind. To determine if a topic belonged in our course, we asked whether it would • •

have important biological applications either in organisms or in instrumentation, be intellectually accessible to most students in the time available, D. C. Meredith and J. A. Bolker


914

Table I. Changes in topic emphasis compared to standard course. Semester 1

Semester 2

Included/stressed

Kinematics Dynamics Static torque Energy Stress/strain and fracture Fluids (far more)

Heat transfer Kinetic theory of gases Entropy Diffusion, convection, conduction Simple harmonic motion Waves (sound, optics)

Omitted/de-emphasized

Projectile motion Relative motion Rotational motion (Ref. 26) Statics (Ref. 27) Collisions Newton’s law of gravitation Kepler’s laws

Heat engines Magnetism (less) Induction (qualitatively) Atomic physics (instrumentation) Relativity

•

be essential to a coherent physics narrative, e.g., acceleration is essential to understanding forces.

The resulting list of topics differs substantially from that in a traditional syllabus and is summarized in Table I. Some traditional topics are covered in less detail since the biological applications are sparse (e.g., two-dimensional elastic collisions), relatively trivial (falling maple seeds as an example of rotational motion), or too difficult to be taught at this level (projectile motion with drag). Our list is shaped by our own interests as well as our students’; we offer it as an example, not a universal prescription. The approach we took to generating it, however, should be widely applicable.24,25 Some traditional, beautiful, and interesting topics in the introductory physics course must be cut to make room for less standard topics, such as fluids, that are essential for biologists; for a physicist, this is like being asked to choose your least favorite child. The choice was made a little easier by our realization that some standard topics are simply not vital for this audience. Such difficult decisions illustrate the constant tension between the instructor’s sense of beauty and coherence of their chosen subject and students’ demand for personal relevance. This happens in all fields and is a particular challenge in a service course, whether for engineers or biologists; we need to find the best balance possible. While we can reasonably expect a student to be willing to listen to an hour’s lecture on a beautiful physics topic with no obvious application, it is unfair to ask her to invest hundreds of hours, great effort, and inevitable pain and frustration in learning material in which she sees neither beauty nor utility. In cases where we retained topics that were needed primarily to support a coherent story line, we focused on problems that, while not biologically based, were accessible and relevant to most students. For instance, kinematics problems based on cars—safe following or passing distances, accident reconstruction—are a good standby when biological applications are lacking. The choice of topics is complicated by the wide range of biological applications. At our institution, biology faculty often call for a one-semester physics course that will “hit all the high points,” but cannot agree on what those high points are. Biologists working at the cellular level have different priorities (e.g., diffusion, viscosity, energy, entropy) than those who work at the organismal level (e.g., energy, torque, 915


ray optics, convection). Covering all the topics on the combined list would require at least two, and possibly three, semesters of physics instruction. Moreover, we ignore at our peril the extensive literature5,14,28 documenting the essential distinction between what we “cover,” especially at superficial depth and high speed, and what students actually come to understand in any useful way.

D. Biologically motivated themes Beyond the essential topics, there are critical themes that should be woven through the IPLS course: scaling, estimation, and gradient driven flows. Size and scale. The importance of size and scale in biology has long been recognized,29 but the standard physics course addresses neither. Most topics offer some opportunity to point to scaling and/or size effects. For example, gravity matters a lot to us but comparatively little to a flea; the opposite is true of surface tension. Estimation and quantitative thinking. Biology students need more opportunity to gain experience, competence, and comfort with quantitative thinking,30 and the IPLS course offers an ideal venue. One key use of estimation for biologists is in assessing what elements of the system matter most; if the viscous drag on a fish is orders of magnitude less than the pressure drag, then only the latter matters, so streamlining will be useful even if it increases total body surface area. But for a tiny water flea, pressure drag, and therefore body shape, is insignificant. The use of estimation in turn brings up a key epistemological issue: understanding when approximations are useful. The following is an example of a biological situation where students must figure out what matters: Forces in air versus water: We talked about jellyfish that get around by taking in water and squirting it back out. Describe at least two things that would be different if there were an organism that got around in air by doing the same thing. Would these differences make it easier or harder to get around? Gradient driven flows. These are a pervasive theme in biology, particularly in physiology and cell biology. Examples include oxygen in lungs, exchange of nutrients and D. C. Meredith and J. A. Bolker


915

waste across the lining of blood vessels and intestines, and transport across cell membranes.31 Students readily connect physics concepts in this area to what they already know about cell membrane structure and function. E. Mathematics Life science students need to strengthen their quantitative reasoning skills,2,3,5 and an algebra-based physics course provides many occasions to do so. However, two issues prevent students from taking full advantage of these opportunities. First, many students have not used algebra or trigonometry for years or have significant gaps in their background. Second, for a significant fraction of biology majors, mathematics is a foreign and often intimidating language; they are not predisposed to using mathematics as a tool for understanding. To address the issue of weak or distant background, we offered online tutorials.32 Three quarters of our students found tutorials to be helpful; 23% already knew the material well enough to do without, and 2% still felt ill-prepared for the mathematics in the course. We highly recommend such tutorials on prerequisite mathematics, as we often found significant unexpected gaps in students’ background knowledge. To address the second mathematical challenge, we sought to motivate students to see mathematics differently; we wanted them to understand equations as more than just a way to get numbers. One common approach to connect meaning and mathematics is the use of proofs. Physicists gain a deep understanding of the implications and utility of an equation from working through a proof and assume students will as well. However, research on students’ perspectives has shown that “proofs are only convincing to teachers and others who are informed about particular formats and rituals.”33 It is counterproductive to spend lecture time on derivations that we never intend or expect students to perform; it only reinforces the notion that physics is about manipulating equations rather than about understanding the world. One important way to help students connect meaning and mathematics is through Modeling Instruction labs that require students to model their own data with an equation and devise a verbal link between the physical world and the equation.21 Quantitative relationships can also be motivated via lecture demonstrations or appeals to experience. For example, given the microscopic explanation of pressure drag as the result of collisions with fluid molecules, students readily understand that surface area of the moving object matters but its mass does not. An alternative to formal proofs is to “unpack” equations in order to build understanding of physical relationships and their mathematical representation.34,35 This strategy familiarizes students with the terms and mathematical relationships and helps them see what really matters. For example, we have used the equation for energy conservation as the framework for a lecture on locomotion, in which we examine each term and relate it to specific ways animals minimize the cost of moving around. Knowing that kinetic energy depends on mass explains why gazelles have slender legs. The squared velocity term indicates that slowing down significantly reduces energy costs, and thus helps explain why long migrations are undertaken at moderate, not maximum, speeds. IV. BIOLOGICAL APPLICATIONS AND PROBLEMS Because life science students are not readily engaged by questions about blocks sliding on ramps or other simple 916


physics examples for which they can imagine no interesting application, we focused on developing and deploying biological applications for the IPLS course. Improving the IPLS course requires labs and problems that keep biology students engaged and motivated, and also demonstrate that physics is, in fact, directly applicable to biological phenomena. Simply painting a cow face on a sphere or pouring salsa over a meatloaf is not enough. To be taken seriously by our students, applications must be clearly important to biology, detailed, and represent a significant fraction of the course grade (including exams). The biggest challenge in developing biologically relevant problems for the IPLS course is that there is a very fine line between physics problems with only superficial biological connections and problems that invoke too much physics or are too complex. It is relatively easy to invent questions we would classify as “superficial applications.” For instance, we could ask, “If animal x can jump 1.3 m high, what must its initial velocity be?” To a biologist, this is grossly oversimplified, and does not address essential concerns such as how the animal’s structure is related to its jumping ability. Not every organism jumps the same way; a flea, a human, and a horse have very different ways to get 1.3 m above the ground. Less superficial textbook examples take the form of an engaging color photo plus a short conceptual explanation or a few homework questions. While these are helpful in pointing out links between biology and physics, they are not enough to improve students’ understanding of deeper and more quantitative connections between the fields. But we can also err on the other side, posing questions that are so complex and full of biological information that students are overwhelmed or distracted from the fundamental physics issues. Although most IPLS students are biology majors, they have diverse backgrounds so we cannot assume any particular biological knowledge. Moreover, the average physics instructor would not be confident using biologically rich questions. A related complication is that questions about biological systems sometimes elicit biological, rather than physical, answers. To discourage these responses, our test questions with obvious biological applications explicitly noted that the question referred to a model and not an actual biological structure. The following question is an example of a round cow: it has clear connections to biology but omits much of the complexity of the real biological system: Gradient-driven flows: Potential across a membrane. This is an ideal situation (as we had in lab); it is NOT meant to describe a real cell membrane (though there are some similarities). (1) You have a membrane with pure water on the left side and Kþ ions on the right side. The membrane is permeable to Kþ. (a) What gradients, if any, are present in this situation? (b) Will the Kþ move? If so, in what direction and why? (c) If there is net motion of Kþ, when will it stop (if at all) and why? If there is no net motion, why not? (2) You have a membrane with Naþ on the left side and Kþ ions on the right side (equal numbers of ions on both sides). The membrane is permeable to Kþ only. D. C. Meredith and J. A. Bolker


916

(a) What gradients, if any, are present in this situation? (b) Will the Kþ move? If so, in what direction and why? Is there a net motion of Kþ? (c) If there is a net motion of Kþ, when will it stop (if at all) and why? If there is no motion, why not? In accordance with Bio 2010’s (p. 48) exhortation, we worked with other faculty to identify rich and meaningful applications to incorporate into the IPLS course. We consulted with colleagues from many areas of biology in order to develop a broad range of applications, and we drew on several biology books with strong physics components.36 A side benefit of our conversations with biologist colleagues was getting feedback on our IPLS course and discussing coverage of the physics they used in their own courses. When biologists provided examples we used in the course, we credited them in class both out of gratitude and as a way of signaling to the students that their biology faculty also care about physics. We focused on animal, plant, and cellular applications, as human applications were already available.37,38 Along the way, we identified key traits of good biological applications for the IPLS course. These applications should • •

• • •

•

balance tractability with applicability to biological contexts; connect to central biological topics such as physiology, structure and function, and adaptation that help students connect physics to their existing biological knowledge; incorporate overarching concepts such as quantifying, modeling, rates, gradients, and scaling; provide sufficient but not irrelevant biological context and be factually correct; relate to other problems focusing on the same key idea, such as pushing on the environment to move (just as a traditional course offers multiple problems illustrating core ideas such as Newton’s second law); integrate concepts from many realms (e.g., geometry, forces, energy), while avoiding cognitive overload.

The problems we wrote are complex; students need to coordinate biological, mathematical, and physical concepts and laws. The problems are by nature unique as they describe a single biological system, though we provide several biological applications for each physics principle. For example, analyzing different ways that animals push on the environment presents the impulse momentum theorem in several guises. Writing such questions is challenging. Unlike questions in a more abstract context, it is not a simple matter to devise multiple questions that are isomorphic and still biologically realistic. Since these problems are difficult to grade individually, and likely impossible to grade for a large class, we recommend the methods suggested by others19,42 to grade for effort and then publish solutions for students to analyze as a source of detailed feedback. In addition to developing biological application problem sets, we created several other kinds of resources that link biology and physics: lectures with clicker questions, annotated bibliographies of biological resources, and labs. These are available as editable files.34,35 V. OUTCOMES AND ASSESSMENT Our primary goal was to make the course thoroughly interdisciplinary, and thus more relevant and engaging to life sci917


ence students. Secondary goals included improving students’ conceptual understanding, ability to connect meaning and mathematics, and epistemological stance. We measured progress toward these goals in several ways. A. Student attitudes and beliefs A standard assessment of student attitudes and beliefs in physics classes is the Colorado Learning Attitudes about Science Survey (CLASS)40 that measures students’ personal epistemologies about science. This Likert-scale survey asks students to agree or disagree with statements reflecting attitudes toward science, e.g., “To understand physics, I sometimes think about my personal experiences and relate them to the topic being analyzed.” The 33 questions are grouped into 8 subcategories such as “real world connections” and “sense making/effort.” Pre and post testing results are quoted as changes toward (positive) or away from (negative) the expert-like attitudes. In both traditional and reformed algebra based courses, changes range from 9.8% to þ1.4%.41 However, courses with a strong epistemological focus have produced significant positive changes in student attitudes.19,42 Overall, our students moved 3:3%61:1% away from expert beliefs. The best result was an insignificant change (1:3%62:8%) for the category of “real world connections,” the category where we put the most emphasis. Because the CLASS does not specifically measure students’ appreciation of the role of physics in biology, we supplemented it with Likert and open-ended surveys. The number and difficulty of biology applications in our course aligned well with student interest (Fig. 1). Moreover, students found the biology applications interesting, relevant to their other courses and planned career, and helpful to understanding the physics (Fig. 2). Responses to open-ended questions included the following: •

•

•

Biology applications made the class much more “worth my time” and made me feel that a seemingly non-relevant major requirement actually did relate to my major. The biology applications were helpful in examples to describe the physics behind it. I think I was more comfortable with the biology explanations and by knowing how to explain it with biology I could better understand the physics side of it. The biological applications… were completely relevant. Not only were the applications extremely interesting, but I think they helped students (including myself) connect adaptation abilities, and more importantly, evolutionary sequences of the natural world of organisms. Organisms understand physics incredibly well; this is how they thrive and survive. I think in order for a biology student to be successful in the future, one must make these connections at an early stage in his/her career.

The overall interest in biological applications was greater than their perceived relevance (Fig. 2). Several students noted “Although I didn’t use [physics] that much [in biology classes] the biology application made it MUCH more interesting for me.” While including biology certainly makes the physics more palatable, life science students may still question why they are required to take a year-long course. D. C. Meredith and J. A. Bolker


917

Fig. 1. Student perceptions of the appropriateness of the number and difficulty of the biological applications.

We used a multiple choice question to probe changes in students’ perceptions about the usefulness of physics in biology, with these results: (1) My perception of connections has changed very little as a result of this course (17.2%). (2) It has become much more evident to me how much biology is dependent on physical principles (28.4%). (3) My understanding of the actual physical mechanisms within biology has improved since I’ve taken this course, though I knew beforehand that they were connected (54.4%). Students clearly found the interdisciplinary nature of the course valuable, even though many were already aware of connections between physics and biology.

Although student responses were generally positive, the course was not universally well received. For example, 9% of students would have preferred to have had less or no biology in the physics class. They gave a variety of reasons such as the biology was confusing, it did not help them understand the physics, it made the physics harder, or it simply did not belong in a physics class. Some students were concerned that they were getting less physics because class time was spent on biological topics. Another concern, voiced by 14% of the students, was that the course was not integrated enough. In particular, the lectures by the biologist (J.A.B.) were on separate days from “regular” physics lectures; we also have different teaching styles. Our survey conflicts with the CLASS results: our survey shows 28% of students began to see more connections with biology, where the CLASS shows no significant change in

Fig. 2. Student answers to Likert-scale questions: (a) “I found the biological applications interesting,” (b) “I found the biological applications relevant to my other courses and/or my planned career,” and (c) “I found the biological applications helped me understand the physics.” 918


D. C. Meredith and J. A. Bolker


918

students’ belief that physics applies to real life. We suggest two possible explanations. First, the CLASS is not focused on biology in particular, so students may have been thinking about other applications (e.g., cars, toaster ovens) about which their opinions did not change. Second, the CLASS was administered in Fall 2010 after only one semester; our surveys were administered in the spring semester, which included many biological examples that students found intriguing.

B. Do students learn to integrate physics and biology? To investigate this core question, we looked at responses to the “Forces in air and water” question detailed above. We wanted to determine if our students could look at a biological system through a physics lens, ignoring its biological complexity, and identify the essential physics. Our students (N ¼ 237) applied many relevant physics principles in their answers: (1) Half mentioned that the push from squirting out air would be far less than the push from squirting out water due to the lower density of air. Some went on to note that faster or more frequent squirting would increase the push. (2) Nearly half of the students mentioned that buoyancy would be smaller in air. A few then concluded that this would result in the animal being on the ground and having to deal with friction. (3) Forty percent of the students noted that the drag force would be smaller in air, making it easier to get around, though many incorrectly cited viscous rather than pressure drag. In summary, 91% of the students were able to describe at least one key physical difference between motion in air and water, demonstrating that they can in fact see the physics in a biology question. Only 3% of the students brought in unnecessary biological complexity. A student’s answer to a different question provides additional evidence of the ability to negotiate the physics/biology distinction: Q: Bats, mice, dogs, and some other mammals are capable of detecting higher-frequency sound waves than we are. Does that mean they can hear sound signals faster or sooner than we do, assuming we are standing in the same place? Explain your reasoning. (This is not about reaction or processing time, just about physical receipt of the signal.) A: Animals that hear a higher frequency do not hear sound signals faster or sooner than we do because frequency does not affect the speed of sound signals. They simply have ears that can detect frequencies at different vibrations than we can, but it has nothing to do with the speed of the signals. This student distinguished clearly between the biology and the physics: she answered the physics first and went on to add closely related biological information. We have many 919


examples of similarly good answers from students who weave together physics and biology in useful ways.34,35 We have additional examples of student work that exemplify students’ ability to make their own connections between biology and physics. These data come from a final exam question that asked students to connect biology and physics. Another source of data is an assignment in the evolution course taught by J.A.B., in which students invent new species. Several students have used physics in these papers, indicating that they see physics as one source for explaining biological form and function. Here are two examples of student responses: From an exam question asking for an example of applications of physics principles. Giving a shot too quickly is bad because the high concentration of the antibiotic or vaccine needs time to soak in as the syringe is depressed. This is especially important in euthanasia because too great a volume of the chemical in too short a time could cause a non-peaceful and painful death. From a fictional species paper in the evolution course. Electriatus musae—This [mouse] species also possesses traits unique within the Muridae family. Predominantly, it is capable of harnessing and manipulating static electricity. The fur of this creature is a thick double coat with outer guard hairs to shed the perpetual ocean mist about its habitat and a loose dry inner coat that keeps in heat and generates a small static charge as the rodent moves. The rodent can release this charge with some accuracy by pointing specialized, mobile, whiskers up to 10 in. away. The transmission of the charge is made possible by the ever-present saltwater mist, which will conduct electricity for small distances. The foot pads of this rodent are thick and non-conductive, effectively trapping accumulated charge for defensive or offensive use. An over-accumulation of static charge can stress the rodent’s cardiovascular system, despite surprising resilience to electric overstimulation in that organ system. If that happens, E. musae will ground itself by touching its tail to the ground, therefore, dispersing the charge (S. Jabobus, author; used with permission).

C. Connecting meaning and mathematics We assessed students’ ability in this realm through many exam questions. For example, a question related to Newton’s law of cooling TðtÞ ¼ Bet=C þ D

(1)

was connected to a lab in which students took data from cooling temperature probes and then modeled their data with an exponential function, connecting parameters with the physical situation. One part of the question asked which parameter changes when the insulation is increased; 69% of students answered correctly. This parameter was also emphasized in the study of damped oscillations, and several students explicitly connected the cooling and damping curves. Students did less well on connecting the other parameters to physical variables. D. C. Meredith and J. A. Bolker


919

One possible inference is that two exposures to the same idea was significantly better than one. Anecdotal evidence that we were achieving our goal came from a group that was videotaped during the lab. One group member commented that “It’s kinda cool way to make us figure out this equation,” to which his lab partner responded “It actually makes a lot of sense.” D. Conceptual understanding To measure conceptual understanding, we used the Force and Motion Concept Evaluation (FMCE)43 and the Test of Understanding Graphs in Kinematics (TUG-K).44 Although these tests do not examine concepts of particular importance to biology students, they do provide a measure of students’ conceptual learning. The TUG-K pre-instruction score average was 34%, and the post-instruction average was 55%, representing a gain of 33.5% (N ¼ 752). The gain is defined as hgi ¼

ðpost percent averageÞ ðpre percent averageÞ 100 ðpre percent averageÞ (2)

and is designed to allow comparisons between classes with different pre-test scores. The TUG-K gains are fairly constant over the 4 yr, whereas the FMCE gains are mixed. Scores improved over the years, with the average gain in Fall 2010 of 24% (N ¼ 299). Gains varied significantly across conceptual categories: velocity graphs (42%), acceleration graphs (28%), energy (58%), and Newton’s third law (34%) for our students were encouraging. Gains in force graphs, force sleds, and reversing direction were closer to 15% and show need for further improvement. For comparison, FMCE gains for reformed courses range from 33% to 93%.45 E. Summary Student attitudes and beliefs about the interdisciplinary features of our course are very positive, with 90% of the students satisfied. Over 90% showed some ability to see physics in a biological situation, and many deftly combined physics and biology in useful and/or novel ways. We conclude that the interdisciplinary nature of the course was successful. The CLASS results show that students have maintained a belief that physics has real world connections. Gains on the TUGK and the FMCE were modest at best; however, these assessments do not sharply focus on our main objective.46 There is a clear need to develop more assessment tools that focus on physics knowledge, skills, and attitudes that are central to biology students.47 VI. CONCLUSIONS AND DISCUSSION There can be no general formula for an “ideal” IPLS course since so many essential elements, from staffing to syllabus, depend heavily on local needs and resources. We can, however, identify some key strategies for success. Rethink organization and topics. Traditional introductory physics courses often start with kinematics. But in the IPLS class, it may work better to begin instead with energy, which has more immediate biological applications. Standard topics may be best taught in new contexts. For example, kinematics and dynamics can be presented mainly in the context of fluids, where many important and biologically relevant forces 920


come into play, offering a wide range of engaging examples and applications. Think carefully about what to cover. The list of topics in a standard calculus-based course or introductory textbook aligns poorly with biology students’ needs. Those needs are, however, well known to colleagues who teach biology classes in which students should find physics useful; seek their input. Collaborate with biologists. Ideally, recruit a local biologist as a co-instructor. If that is not possible, invite biologist colleagues as guest speakers. At a minimum, use them as a source of background information about biological applications of physical topics. For instance, work with a cell biologist to develop relevant applications of thermodynamics topics such as entropy and enthalpy that are accessible to IPLS students with minimal mathematics. Interdisciplinarity is, by definition, a two-way street. Besides making the physics course more relevant and appropriate for biologists, we need to encourage biology faculty to call upon the physics we teach in the IPLS course. As one of our students pointed out, [B]iology professors don’t place emphasis on physical concepts, and those that do assume no physics knowledge of their students. Perhaps requiring that physics be taken Freshman or Sophomore year would allow upper-level biology class professors to assume basic physics knowledge in their students, allowing them to incorporate the concepts into their curriculum if desired. We can provide instructors of advanced biology courses with an overview of what students who have taken the IPLS class should already know about key topics. We can also encourage instructors in the freshman biology course to point forward to these topics. Moving physics earlier in the curriculum poses a greater challenge, as the first two years of the biology curriculum are often filled by mathematics, chemistry, and introductory biology. Acknowledge limitations. Recognize administrative structures that impose constraints or offer opportunities. Despite high-level calls for interdisciplinary teaching and learning, much work remains to be done at ground level. We believe that a truly integrated IPLS class is best taught by a physicist and a biologist together, and our local circumstances and NSF funding enabled us to do that for several years. However, limited resources often preclude such arrangements. What is best for students in the long run may be too costly for departments in the short term. Institutions claiming to value interdisciplinary collaboration need to develop ways to acknowledge and reward such activities, both for individual faculty and for their departments. For example, a biologist helping to teach a physics class should receive formal credit for that teaching effort, even though it is in a foreign department. Compensating faculty for additional teaching may be beyond the means of many institutions. We should recognize, however, that few important investments are free. On the positive side, where institutions (or funding sources) offer explicit support for interdisciplinary teaching and research, we can make a strong case for investing it in the IPLS course. Physics and biology faculty benefit from sharing perspectives, disciplinary knowledge, and teaching strategies. Biology students benefit from a deeply integrative course in which they gain not only new quantitative skills and physical knowledge but the ability to apply them in their chosen field. D. C. Meredith and J. A. Bolker


920

Use the research. We say this again because it bears repeating: draw on the extensive research of learning and teaching to improve pedagogy.5,14 Such strategies are especially useful in an IPLS course, where students may lack both the background and the motivation to readily master new concepts and problem-solving skills. Future work. We made progress in shaping our IPLS course to meet the needs of our students, but much remains to be done. Better integration of biology themes and smoothing the edges between biology and physics would make for a more integrated course. We must also become more realistic about what we can accomplish in one course. Although we skipped many “standard” physics topics, our agenda was still too long. Teaching the remaining topics effectively, while also improving students’ skills and attitudes, was at times overwhelming. But real progress will ultimately require addressing and integrating all the goals. One possible model for ongoing course development is described by the evolutionary principle of correlated progression. This pattern of evolution is not driven by massive changes in single traits; rather, “all the traits are functionally linked and so constrained to evolve by small increments at a time in parallel with each other.”48 In the face of diminishing resources, increased teaching requirements, and obstacles to granting workload credit for shared courses, we have been unable to continue teaching our collaborative IPLS class at UNH. We hope other faculty and institutions can devise a sustainable model and that our insights and resources will prove useful to that effort. Designing and teaching a rigorous, effective, and engaging IPLS course is hard, and many challenges remain. Nevertheless, external calls for change resonate with our own conviction that we can do better than the traditional introductory course to help life science students learn and appreciate physics. ACKNOWLEDGMENTS The authors gratefully acknowledge the collaborators on this grant: Gertrud Kraut, James Vesenka, and Christopher Shubert. Helpful editorial suggestions were provided by Ethan Bolker and Robert Hilborn. The work was supported by the National Science Foundation under Grant No. 0737458. a)

Electronic mail: [email protected] O. Blu¨h, “Physics for the biologist,” Am. J. Phys. 29, 771–776 (1961); P. Argos, “General physics course for pre-medical students,” Am. J. Phys. 41, 1224–1229 (1973); W. G. Buckman, J. E. Parks, and T. P. Cohill, “An introductory physics and biophysics course for life science students,” Am. J. Phys. 43, 77–80 (1975); G. Kortemeyer, “The challenge of teaching introductory physics to premedical students,” Phys. Teach. 45, 552–557 (2007). 2 Committee on Undergraduate Biology Education to Prepare Research Scientists for the 21st Century, Bio 2010: Transforming Undergraduate Education for Future Research Biologists (The National Academies Press, Washington, DC, 2003). 3 AAMC-HHMI Committee, Scientific Foundations for Future Physicians (American Association of Medical Colleges, Washington, DC, 2009). 4 The MCAT MR5 preliminary recommendations are available on the AAMC website at . 5 Vision and Change reports, presentations, and working group information from the 2009 meeting can be found at . 6 Detailed examples can be found in the AAMC-HHMI report. 7 A list of physics topics covered and a sample physics portion of the MCAT is available online at . 1

921


8

The OAT practice test can be found online at . The Dental Admissions Test (DAT) does not have a physics component. 9 A. Y. Zheng, J. K. Lawhorn, T. Lumley, and S. Freeman, “Application of Bloom’s taxonomy debunks the ‘MCAT Myth,’” Science 319, 414–415 (2008). 10 The MCAT exam includes passage questions that introduce physics phenomena or concepts that few students will have learned about in class, such as bremsstrahlung (the subject of the passage problem in the current practice test). These passages build on fundamental ideas such as probability and conservation of energy, thus allowing students to construct a working understanding of the new topic on the spot. Several of our students who took the exam confirmed that it probes comprehension rather than mere recall. 11 C. H. Crouch, R. Hilborn, S. A. Kane, T. McKay, and M. Reeves, “Physics for future physicians and life scientists: A moment of opportunity,” APS News 19, 3 (2010). IPLS course syllabi and working documents from the Fall 2009 IPLS conference can be found at . 12 From one of our students on anonymous course feedback. 13 D. K. Gosser, M. S. Cracolice, J. A. Kampmeier, V. Roth, V. S. Strozak, and P. Varma-Neslon, Peer-Led Team Learning: A Guidebook (Prentice Hall, Upper Saddle River, NJ, 2001). 14 J. D. Bransford, A. L. Brown, and R. R. Cocking, How People Learn: Brain, Mind, Experience, and School (National Academies Press, Washington, DC, 2003); J. Handelsman, S. Miller, and C. Pfund, Scientific Teaching (Roberts and Co., New York, 2007); E. F. Redish, Teaching Physics with the Physics Suite (John Wiley & Sons, Hoboken, NJ, 2003); R. D. Knight, Five Easy Lessons: Strategies for Successful Physics Teaching (Addison Wesley, San Francisco, CA, 2004). 15 L. C. McDermott, “Millikan lecture 1990: What we teach and what is learned—Closing the gap,” Am. J. Phys. 59, 301–315 (1991). 16 E. Mazur, Peer Instruction: A User’s Manual (Addison-Wesley, San Francisco, 1997). 17 P. Heller, R. Keith, and S. Anderson, “Teaching problem solving through cooperative grouping. Part 1: Group versus individual problem solving,” Am. J. Phys. 60, 627–636 (1992). Their website has a library of context rich problems at . 18 R. D. Knight, B. Jones, and S. Field, College Physics, A Strategic Approach (Pearson, Addison Wesley, San Francisco, CA, 2007). 19 E. F. Redish and D. Hammer, “Reinventing college physics for biologists: Explicating an epistemological curriculum,” Am. J. Phys. 77, 629–642 (2009). 20 Open source tutorials focused on helping students refine their intuitions, developed by Andrew Elby and Rachel Scherr, are available at . This site also has annotated videos and instructor’s guides. 21 M. Wells and D. Hestenes, “A modeling method for high school physics instruction,” Am. J. Phys. 63, 606–619 (1995). 22 J. Vesenka (in preparation). 23 A new IPLS textbook (published after we began our project) that does pay close attention to the needs of biologists is J. Newman, Physics of the Life Sciences (Springer, New York, NY, 2008). Another new text by Tim McKay is in preparation. 24 See the working documents from the 2009 IPLS conference, Competency E3, Teaching IPLS Physics Content. 25 See p. 37 in Bio2010 for a full list of recommended topics, which largely overlaps ours. 26 Biologists are interested in motion in partial circles, e.g., joints moving in their normal range of motion. Objects moving in full circles with constant acceleration are almost non-existent in biology. 27 Biologists tend to be interested in static torque questions, e.g., what forces must muscles exert to hold a specified weight. However, statics problems involving ladders against walls and hanging signs are less relevant. 28 D. Hammer, “Two approaches to learning physics,” Phys. Teach. 27, 664–670 (1989). 29 J. B. S. Haldane, “On being the right size,” in Possible Worlds and Other Essays (Harper and Brothers, New York. 1928); M. Kleiber, The Fire of Life: An Introduction to Animal Energetics (John Wiley and Sons, New York, 1961); T. A. McMahon and J. T. Bonner, On Size and Life (Scientific American Library, New York, 1983); C. J. Pennycuick, Newton Rules Biology: A Physical Approach to Biological Problems (Oxford U.P., Oxford, UK, 1992); E. M. Purcell, “Life at low Reynolds number,” Am. J. D. C. Meredith and J. A. Bolker


921

Phys. 45, 3–11 (1977); D. W. Thompson, On Growth and Form (Cambridge U.P., Cambridge, UK, 1972); S. A. Wainwright, W. D. Biggs, J. D. Currey, and J. M. Gosline, Mechanical Design in Organisms (Edward Arnold Reprint, London, UK; Princeton U.P., Princeton, NJ, 1976). 30 See Bio2010, p. 4. 31 T. Cooke and J. Redish, University of Maryland, personal communication. 32 We used existing mathematical tutorials in MasteringPhysics and several written by our mathematics colleague Professor Gertrud Kraut. 33 S. M. Soucy McCrone and T. S. Martin, “Formal proof in high school geometry: Student perceptions of structure, validity, and purpose,” in Teaching and Learning Proof Across the Grades: A K-16 Perspective, edited by D. A. Stylianou, M. L. Blanton, and E. J. Knuth (Routledge Taylor & Frances Group, New York, 2009), pp. 204–221. 34 Our website is a repository for several kinds of curricular materials: lectures, peer instruction questions, annotated bibliographies, and problem collections. In addition, we include student work that connects biology and physics. . 35 See supplemental material at http://dx.doi.org/10.1119/1.4733357 for curricular materials: lectures, peer instruction questions, annotated bibliographies, and problem collections. 36 S. Vogel, Comparative Biomechanics: Life’s Physical World (Princeton U.P., Princeton, NJ, 2003); J. W. Bradbury and S. L. Vehrencamp, Principles of Animal Communication (Sinauer Associates, Sunderland, MA, 1998); M. W. Denny, Air and Water: The Biology and Physics of Life’s Media (Princeton U.P., Princeton, NJ, 1993); S. Vogel, Life in Moving Fluids (Princeton U.P., Princeton, NJ, 1994); S. Vogel, Vita Circuits: On Pumps, Pipes and the Workings of Circulatory Systems (Oxford U.P., New York, NY, 1992); R. Ennos, Solid Biomechanics (Princeton U.P., Princeton, NJ, 2012); S. Johnsen, The Optics of Life: A Biologist’s Guide to Light in Nature (Princeton U.P., Princeton, NJ, 2012). 37 Humanized Physics Project laboratories and activities can be found at . 38 S. A. Kane, Introduction to Physics in Modern Medicine (Taylor and Francis, London, 2003). 39 Two higher level physics texts with extensive biology applications are G. Benedek and F. Villars, Physics with Illustrative Examples from Medicine and Biology (AIP Press, Springer Verlag, New York, NY, 2000);

922


P. Nelson, Biological Physics: Energy, Information, Life (W. H. Freeman and Company, New York, NY, 2008). 40 W. K. Adams, K. K. Perkins, N. S. Podolefsky, M. Dubson, N. D. Finkelstein, and C. E. Wieman, “New instrument for measuring student beliefs about physics and learning physics: The Colorado learning attitudes about science survey,” Phys. Rev. ST Phys. Educ. Res. 2, 010101 (2006). 41 K. K. Perkins, W. K. Adams, N. D. Finkelstein, S. J. Pollock, and C. E. Wieman, “Correlating student attitudes with student learning using the Colorado learning attitudes about science survey,” in 2004 Physics Education Research Conference Proceedings, edited by J. Marx, P. Heron, and S. Franklin (AIP, Melville, NY, 2005), Vol. 790, pp. 61–64. 42 A. Elby, “Helping physics students learn how to learn,” Am. J. Phys. 69, S54–S64 (2001). 43 R. K. Thornton and D. R. Sokoloff, “Assessing student learning of Newton’s laws: The force and motion conceptual evaluation and the evaluation of active learning laboratory and lecture curricula,” Am. J. Phys. 66, 338–352 (1998). We chose the FMCE over the better known force concept inventory (D. Hestenes, M. Wells, and G. Swackhamer, “Force concept inventory,” Phys. Teach. 30, 141–158 (1992)) because the FCI has many two-dimensional questions (e.g., projectile motion and circular motion) that we did not emphasize (see Table I). 44 R. J. Beichner, “Testing student interpretation of kinematic graphs,” Am. J. Phys. 62, 750–762 (1994). 45 R. K. Thornton, D. Kuhl, K. Cummings, and J. Marx, “Comparing the force and motion conceptual evaluation and the force concept inventory,” Phys. Rev. ST Phys. Educ. Res. 5, 010105 (2009). 46 Work by D. J. Wagner on developing a fluids assessment, which is more closely linked to needs of biology students, is available online at . 47 A summary of the IPLS FAll 2009 working group on the need for different assessment is located on the IPLS wiki at . 48 T. S. Kemp, “The concept of correlated progression as the basis of a model for the evolutionary origin of major new taxa,” Proc. R. Soc. London, Ser. B 274, 1667–1673 (2007).

D. C. Meredith and J. A. Bolker


922