We conducted a controlled investigation to examine whether a combination of computer imagery and tactile tools helps introductory cell biology laboratory undergraduate students better learn about protein structure/function relationships as compared with computer imagery alone. In all five laboratory sections, students used the molecular imaging program, Protein Explorer (PE). In the three experimental sections, three-dimensional physical models were made available to the students, in addition to PE. Student learning was assessed via oral and written research summaries and videotaped interviews. Differences between the experimental and control group students were not found in our typical course assessments such as research papers, but rather were revealed during one-on-one interviews with students at the end of the semester. A subset of students in the experimental group produced superior answers to some higher-order interview questions as compared with students in the control group. During the interview, students in both groups preferred to use either the hand-held models alone or in combination with the PE imaging program. Students typically did not use any tools when answering knowledge (lowerlevel thinking) questions, but when challenged with higher-level thinking questions, students in both the control and experimental groups elected to use the models.

Abstract-We have measured the trace element compositions of individual plagioclase, pyroxene, and olivine grains in 6 different winonaites that span the range of textures and mineralogies observed in these meteorites. Textural evidence in these meteorites, including the presence of a plagioclase/ clinopyroxene-rich lithology and coarse-grained olivine lithologies, suggests that they may have experienced some silicate partial melting. However, trace element distributions in these lithologies do not show any clear signatures for such an event. Pyroxene trace element compositions do exhibit systematic trends, with abundances generally lowest in Pontlyfni and highest in Winona. The fact that the same trends are present for both incompatible and compatible trace elements suggests, however, that the systematics are more likely the result of equilibration of minerals with initially heterogeneous and distinct compositions, rather than partial melting of a compositionally homogeneous precursor. The winonaites have experienced brecciation and mixing of lithologies, followed by varying degrees of thermal metamorphism on their parent body. These factors probably account for the variable bulk rare earth element (REE) patterns noted for these meteorites and may have led to re-equilibration of trace elements in different lithologies.

The technology now exists to construct physical models of proteins based on atomic coordinates of solved structures. We review here our recent experiences in using physical models to teach concepts of protein structure and function at both the high school and the undergraduate levels. At the high school level, physical models are used in a professional development program targeted to biology and chemistry teachers. This program has recently been expanded to include two student enrichment programs in which high school students participate in physical protein modeling activities. At the undergraduate level, we are currently exploring the usefulness of physical models in communicating concepts of protein structure and function that have been traditionally difficult to teach. We discuss our recent experience with two such examples: the close-packed nature of an enzyme active site and the pH-induced conformational change of the influenza hemagglutinin protein during virus infection.A common goal of biochemistry educators is to provide students with a deep understanding of fundamental concepts underlying protein structure and function. This is most commonly done by exposing students to stunning two-dimensional color graphics of proteins in textbooks and frequently augmenting these static figures with interactive images that can be rotated in three-dimensional space in a computer environment. Although this approach is successful for those students who are able to infer three-dimensional information from these inherently twodimensional representations, many other students fail to make this inference. For them, the molecular world of proteins remains an abstraction for which they have little interest. We have found that physical models of proteins ( Fig. 1) are amazingly effective tools that initially capture the interest of this larger group of students and motivate them to learn more about this invisible, molecular world. These physical models are synergistic with computer visualization tools, allowing students to generalize their initial understanding of a specific protein to other structures that are explored in a computer environment. We review here our recent experience with the use of physical models to make this molecular world "real" for students at both the high school and the undergraduate levels. A THEORETICAL BASIS FOR THE VALUE OF PHYSICAL MODELS IN TEACHING ABSTRACT CONCEPTS IN SCIENCEThe value of physical models of small molecules in organic chemistry courses is well known to biochemistry educators. However, these small molecule kits are not practical for modeling the higher order molecular structures of proteins. Experienced researchers have learned to infer three-dimensional information from two-dimensional images of proteins or to manipulate interactive, computergenerated images of proteins. Unfortunately, our current educational practice treats inexpert students as though they were expert researchers. Students are introduced to proteins through two-dimensional drawings or interactive computer visualiz...

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How can we get high school students interested in science? Here is a program that matches students with researchers, with the purpose of building a physical model of the protein being investigated in the lab.