Teaching with core concepts to facilitate the integrated learning of introductory organismal biology.

Despite the call from biology educators for students to learn the biological sciences as a unified whole, the teaching of introductory organismal biology is still largely arranged into separate sections that tend to focus exclusively on the biology of individual taxonomic categories (i.e., animals and plants). Conversely, this paper presents a strategy for combining the teaching and learning of introductory animal and plant biology using the core concepts of biology and physiology as tools for integrative learning. The paper outlines the positioning of organismal biology within a two-semester introductory biology course, the topical organization of an integrated organismal biology module around shared physiological functions, the use of core concepts to facilitate the combined learning of the biology of animals and plants, and some instructional practices that can support core concepts as learning tools for organismal biology. Examples of how core concepts serve to integrate the organismal biology of animals and plants are described and explained. The goal of this approach is to show introductory students that the mastery of core concepts can help them integrate their understanding of organismal biology. More broadly, students acquire skills in using core concepts as learning tools in biology that should enable them to better assimilate more advanced concepts and to achieve a more unified study of the biological sciences as they progress through the curriculum.NEW & NOTEWORTHY This paper is 1) a personal view on why the teaching of introductory animal and plant biology ought to be more integrated and how an integrated module for introductory organismal biology can be designed, and 2) a practical guide to instructors on how core concepts can be used as learning tools to promote the integrated learning of introductory organismal biology.

Development and Validation of the Homeostasis Concept Inventory.

We present the Homeostasis Concept Inventory (HCI), a 20-item multiple-choice instrument that assesses how well undergraduates understand this critical physiological concept. We used an iterative process to develop a set of questions based on elements in the Homeostasis Concept Framework. This process involved faculty experts and undergraduate students from associate's colleges, primarily undergraduate institutions, regional and research-intensive universities, and professional schools. Statistical results provided strong evidence for the validity and reliability of the HCI. We found that graduate students performed better than undergraduates, biology majors performed better than nonmajors, and students performed better after receiving instruction about homeostasis. We used differential item analysis to assess whether students from different genders, races/ethnicities, and English language status performed differently on individual items of the HCI. We found no evidence of differential item functioning, suggesting that the items do not incorporate cultural or gender biases that would impact students' performance on the test. Instructors can use the HCI to guide their teaching and student learning of homeostasis, a core concept of physiology.

Validating a conceptual framework for the core concept of "cell-cell communication".

We have created and validated a conceptual framework for the core physiology concept of "cell-cell communication." The conceptual framework is composed of 51 items arranged in a hierarchy that is, in some instances, four levels deep. We have validated it with input from faculty who teach at a wide variety of institutional types. All items making up the framework were deemed essential to moderately important. However, some of the main ideas were clearly judged to be more important than others. Furthermore, the lower in the hierarchy an item is, the less important it is thought to be. Finally, there was no significant difference in the ratings given by faculty at different types of institutions.

A conceptual framework for homeostasis: development and validation.

We have developed and validated a conceptual framework for understanding and teaching organismal homeostasis at the undergraduate level. The resulting homeostasis conceptual framework details critical components and constituent ideas underlying the concept of homeostasis. It has been validated by a broad range of physiology faculty members from community colleges, primarily undergraduate institutions, research universities, and medical schools. In online surveys, faculty members confirmed the relevance of each item in the framework for undergraduate physiology and rated the importance and difficulty of each. The homeostasis conceptual framework was constructed as a guide for teaching and learning of this critical core concept in physiology, and it also paves the way for the development of a concept inventory for homeostasis.

A physiologist's view of homeostasis.

Homeostasis is a core concept necessary for understanding the many regulatory mechanisms in physiology. Claude Bernard originally proposed the concept of the constancy of the "milieu interieur," but his discussion was rather abstract. Walter Cannon introduced the term "homeostasis" and expanded Bernard's notion of "constancy" of the internal environment in an explicit and concrete way. In the 1960s, homeostatic regulatory mechanisms in physiology began to be described as discrete processes following the application of engineering control system analysis to physiological systems. Unfortunately, many undergraduate texts continue to highlight abstract aspects of the concept rather than emphasizing a general model that can be specifically and comprehensively applied to all homeostatic mechanisms. As a result, students and instructors alike often fail to develop a clear, concise model with which to think about such systems. In this article, we present a standard model for homeostatic mechanisms to be used at the undergraduate level. We discuss common sources of confusion ("sticky points") that arise from inconsistencies in vocabulary and illustrations found in popular undergraduate texts. Finally, we propose a simplified model and vocabulary set for helping undergraduate students build effective mental models of homeostatic regulation in physiological systems.

Chemistry misconceptions associated with understanding calcium and phosphate homeostasis.

Successful learning of many aspects in physiology depends on a meaningful understanding of fundamental chemistry concepts. Two conceptual diagnostic questions measured student understanding of the chemical equilibrium underlying calcium and phosphate homeostasis. One question assessed the ability to predict the change in phosphate concentration when calcium ions were added to a saturated calcium phosphate solution. Fifty-two percent of the students correctly predicted that the phosphate concentration would decrease in accord with the common ion effect. Forty-two percent of the students predicted that the phosphate concentration would not change. Written explanations showed that most students failed to evoke the idea of competing chemical equilibria. A second question assessed the predicted change in calcium concentration after solid calcium phosphate was added to a saturated solution. Only 11% of the students correctly predicted no change in calcium concentration; 86% of the students predicted an increase, and many based their prediction on a mistaken application of Le Chatelier's principle to heterogeneous equilibria. These results indicate that many students possess misconceptions about chemical equilibrium that may hamper understanding of the processes of calcium and phosphate homeostasis. Instructors can help students gain greater understanding of these physiochemical phenomena by adopting strategies that enable students achieve more accurate conceptions of chemical equilibria.

The "core principles" of physiology: what should students understand?

The explosion of knowledge in all of the biological sciences, and specifically in physiology, has created a growing problem for educators. There is more to know than students can possibly learn. Thus, difficult choices have to be made about what we expect students to master. One approach to making the needed decisions is to consider those "core principles" that provide the thinking tools for understanding all biological phenomena. We identified a list of "core principles" that appear to apply to all aspects of physiology and unpacked them into their constituent component ideas. While such a list does not define the content for a physiology course, it does provide a guideline for selecting the topics on which to focus student attention. This list of "core principles" also offers a starting point for developing an assessment instrument to be used in determining if students have mastered the important unifying ideas of physiology.

How the story unfolds: exploring ways faculty develop open-ended and closed-ended case designs.

Open-ended or closed-ended case study design schemes offer different educational advantages. Anatomy and physiology faculty members who participated in a conference workshop were given an identical case about blood doping and asked to build either an open-ended study or a closed-ended study. The workshop participants created a rich array of case questions. Participant-written learning objectives and case questions were compared, and the questions were examined to determine whether they satisfied criteria for open or closed endedness. Many of the participant-written learning objectives were not well matched with the case questions, and participants had differing success writing suitable case questions. Workshop participants were more successful in creating closed-ended questions than open-ended ones. Eighty-eight percent of the questions produced by participants assigned to write closed-ended questions were considered closed ended, whereas only 43% of the questions produced by participants assigned to write open-ended questions were deemed open ended. Our findings indicate that, despite the fact that instructors of anatomy and physiology recognize the value of open-ended questions, they have greater difficulty in creating them. We conclude that faculty should pay careful attention to learning outcomes as they craft open-ended case questions if they wish to ensure that students are prompted to use and improve their higher-order thinking skills.

Is formative assessment an effective way to improve learning? A Symposium at Experimental Biology 2008.

Formative assessment is designed to provide information about students' learning to help them and their teachers to identify deficiencies and misconceptions. It differs from summative assessment, which aims to rank students according to their achievements to determine which students pass or fail or to assign grades to students. This article reports on a symposium concerned with evidence for the effectiveness of formative assessment in improving learning. It was presented by the Teaching of Physiology Section of the American Physiological Society at the Experimental Biology Meeting of 2008.

Case study analysis and the remediation of misconceptions about respiratory physiology.

Most students enter the physiology classroom with one or more fundamental misconceptions about respiratory physiology. This study examined the prevalence of four respiratory misconceptions and determined the role of case analysis in the remediation of one of them. A case study was used to help students learn about oxygen transport in the blood and a conceptual diagnostic test was used to assess student understanding of the relation between Po(2) and hemoglobin saturation by probing for the corresponding (Sa/Po(2)) misconception. A 36% remediation of the Sa/Po(2) misconception was found to be associated with case analysis. This repair was selective since the frequency of three other respiratory misconceptions was found to be unchanged after classroom instruction about respiratory physiology in lectures and laboratories. Remediation of the Sa/Po(2) misconception before an instructor-led, in-class case review was superficial and temporary. Explanations provided by students who correctly answered the Sa/Po(2) conceptual diagnostic test showed improved conceptual understanding following case analysis. These results suggest that a learning strategy where students actively confront their faulty notions about respiratory physiology is useful in helping them overcome their misconceptions.

Case-based learning of blood oxygen transport.

A case study about carbon monoxide poisoning was used help students gain a greater understanding of the physiology of oxygen transport by the blood. A review of student answers to the case questions showed that students can use the oxygen-hemoglobin dissociation curve to make meaningful determinations of oxygen uptake and delivery. However, the fact that many students had difficulty locating the effect of carbon monoxide poisoning in the process of external respiration suggests that these students have not built a robust model of how oxygen distributes itself between the plasma and hemoglobin. This suggests that more determined emphasis on how oxygen enters the blood and how it is partitioned between hemoglobin and the plasma would help students develop more accurate mental models of how oxygen moves from the lungs to the tissues.

Undergraduates' understanding of cardiovascular phenomena.

Undergraduates students in 12 courses at 8 different institutions were surveyed to determine the prevalence of 13 different misconceptions (conceptual difficulties) about cardiovascular function. The prevalence of these misconceptions ranged from 20 to 81% and, for each misconception, was consistent across the different student populations. We also obtained explanations for the students' answers either as free responses or with follow-up multiple-choice questions. These results suggest that students have a number of underlying conceptual difficulties about cardiovascular phenomena. One possible source of some misconceptions is the students' inability to apply simple general models to specific cardiovascular phenomena. Some implications of these results for teachers of physiology are discussed.