About Hands-On Molecular Science (HOMS) Hands on Molecular Science (HOMS) was a small research study funded in 1998 by the National Science Foundation and executed by the Concord Consortium. It was the first of a series of molecular projects, the only one primarily focused on middle school students.
Our Premise
We believe we can better support student understanding of crucial, pivotal themes that undergird science disciplines by developing generalizable cognitive science models that will help them understand many topics in science. We are convinced that understanding a few models of pivotal concepts in great depth, using the latest visualization tools, will allow them to move more easily through other parts of the curriculum.A Pivotal Concept - Structure and Function
A fundamental concept, central to the study of biology, is the connection between structure and function, such as the structure and function of proteins. This example of a pivotal theme, which was be the focus of this proof-of-concept work, is embodied in two Benchmarks (AAAS, 1993, p. 80)
4D7: ...An enormous variety of biological, chemical, and physical phenomena can be explained by changes in the arrangement and motion of atoms and molecules.
4D8: The configuration of atoms in a molecule determines the molecule's properties.Shapes are particularly important in how large molecules interact with each other. Thus the structure of molecules in their 3-D shape is directly related to the function of these molecules as they participate in biochemical reactions.
While the close connection of structure and function is central to the study of biology, it is generally stressed only at the macro level. Application of this concept to the microscopic domain of molecules has been largely overlooked, at least in the pre-college chemistry and biology curricula.
Technology Tools to Support Pivotal Concepts
Using a "hands on" approach to teach students about molecules has been difficult. Though one may easily discover by direct observation the match of the structure of a bird's wing to its function as a lightweight, waterproof airfoil, it is less obvious that there is a connection between the three-dimensional organization of a biopolymer such as a protein, and its biological functionality. Thus, a central paradigm, essential for understanding molecular biology, biochemistry, modern genetics, and biotechnology, is hardly touched upon in the K-12 curriculum.Professional scientists-biochemists, biophysicists, molecular biologists, and genetic engineers-have developed, on the other hand, a powerful mental model for thinking about molecules in living cells: they treat them as micromachines. Mentally shrinking themselves to the size of a small molecule, scientists "view" antibodies intercepting bacterial toxins, hormones facilitating the transfer of ions through a cell membrane, or pharmacological molecules altering an enzyme's affinity to a substrate. They have developed a model of the relationship between the structure of biological molecules and their function in a living cell.
We proposed to develop an innovative technology and pedagogy for teaching these benchmarks in the context of present-day molecular biology and biochemistry, using what Paul Horwitz (Horwitz, 1998) calls computer-based manipulatives: rich, interactive visualizations that help students create mental models at the molecular level that are helpful in understanding, remembering, and predicting macroscopic properties and interactions.
Bridging the Gap
When studying genetics, students learned that the mutation of a single gene can lead to a "mistake" in translation process. A student should be able to reason that when a cell puts the wrong amino acid in the growing protein chain, the mutant cell, whether bacterial or human, may develop a "wrong" protein. The malfunction can lead to different diseases.
By exploring the structure of proteins, students should understand why a replacement of a single amino acid in a protein, for example, when a neutral amino acid is replaced by a positive or neutral amino acid, may lead to a significant change in the physical and chemical properties of the entire molecule.
We believe that this piece, representing the gap between the segment of genetics that extends from gene to protein synthesis, and the part in molecular biology that begins with proteins and their functionality, is often missing in students' reasoning.
Fluency with models
As the central outcome of this project, we wanted students to develop fluency in this world of intra- amd inter- molecular interactions. Fluency includes the development of mental models to understand the concept of molecular conformations and the physical forces behind it. We want students to explore how the spatial arrangement of amino acid groups in a protein determines its three-dimensional structure which in turn determines its biological activity. This would bridge a significant gap between the physical and life sciences curricula, if students learn that cells build these marvelous molecular "machines" simply by arranging their components in the right order; everything else is governed by purely deterministic, physical interactions between the components and their aqueous surroundings.
Partners
Parallel Graphics Inc. worked with us in developing a powerful, simple and focused model of 3-D charged molecules. .Immersion Technologies worked with us on adapting the haptic sensor to molecular structures. We used force feedback to the user by providing a convincingly real haptic (tactile) interaction with computers. We were adapting haptic devices that transmit forces so that when the students move a test charge near a molecule, they can feel the force of attraction or repulsion due to the presence of positive or negative charge.
