Design and Evaluation of a Multimodal Representation for Conveying the Vast Range of Imperceptible Smallness

Design and Evaluation of a Multimodal Representation for Conveying the Vast Range of Imperceptible Smallness

Minyoung Song (University of Michigan, USA)
DOI: 10.4018/978-1-4666-1628-8.ch007


Teaching and learning the vast range of the sizes that are too small to see (called imperceptible sizes) has been a challenging topic, and a need for a novel form of representation that may provide learners with an alternative way of perceiving and conceptualizing imperceptible sizes emerged. From this, the author introduces a multimodal representation called Temporal-Aural-Visual Representation (TAVR). Unlike commonly used conventional representations (e.g., visual representation), TAVR employs a temporal modality as the main vehicle for conveying imperceptible sizes. In this chapter, the author elaborates on the design process and the details of TAVR. Informed by cognitive psychology research, the mental model and the challenges for learners in understanding imperceptible sizes were identified to form the design requirements of TAVR. Following the design and implementation, the evaluation of TAVR aimed to assess the changes in the participating students’ mental model of the range of imperceptible sizes, which showed TAVR’s positive impact on student learning.
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Teaching and learning the sizes of the objects that are too small to see1 (called imperceptible objects) has been a challenging issue in science education. Although there exists a vast range of imperceptible sizes, Research by Tretter, Jones, Andre, Negishi, and Minogue (2006a) shows that middle school students tend to think that the sizes of imperceptible objects (e.g., cells, bacteria, viruses, DNA, molecules, and atoms) are similar with each other, even with the size of a small macroscopic object such as a grain of sand or a dust particle. For example, middle school students classified the imperceptible objects into one “small” group when they are asked to classify a number of objects (including macroscopic) by similar size, while experts divided the objects into at least three different groups; sub-nano, nano, and microscopic objects (Tretter, et al., 2006a). These misconceptions arise mainly because of the nature of human perception; we cannot see imperceptible objects with naked eyes. While people instantly form a visual mental image, which plays a critical role in size perception, of a perceptibly big object when they directly see it, they are unable to generate a visual mental image of something that is too small to see.

Hence, due to this nature that learners cannot have direct and holistic visual experience with imperceptible objects, they have to depend on representations to perceive and conceptualize the sizes of the objects. Representations involve symbols, rules, constraints, and relations embedded in figures such as spatial relations of written digits, visual and spatial layouts of diagrams, even thematic colors of certain items, etc. Such representations may allow a learner to understand concepts which are absent in space and time and to access knowledge and skills that would be beyond his or her cognitive capability. These roles of representations are particularly more important when students learn about imperceptible worlds because what learners perceive and conceptualize is mediated only by the representations they use. No one has ever directly seen what a Hydrogen atom looks like, but representations enable learners to visualize it.

A number of learning technologies have been developed to support learners to understand the vast range of imperceptible sizes. Commonly used learning technologies normally present learners with the representations that are presented in Figure 1. The examples in Figure 1 are created to convey the size of a Hydrogen atom in six different ways. These are commonly used representations among expert scientists and also in science textbooks. The first example is an absolute size of a Hydrogen atom. Experts use measurement units such as micrometer2 or nanometer3 to discuss the absolute sizes of imperceptible objects (e.g., “the diameter a Hydrogen atom is about 0.1 nanometer.”), or one may use relative size (the second example) such as “the diameter of a DNA helix is about 10,000,000,000 times smaller than one millimeter.” The logarithmic scale (third example) particularly aims to convey the range of different sizes. Visual representations (fourth example) perhaps are the most commonly used representations for learners in learning technologies and textbooks. The macroscopic graphics of imperceptible objects are usually aligned in line for size comparison. Interactive visual representations (example not included in Figure 1) present learners with the macroscopic depictions of visual representations such as video (e.g., Powers of Ten) or interactive graphic images (e.g., Scale Ladder). For example, the visual representations of imperceptible objects are enlarged to a visible scale through automatic zooming-in animation or via an interactive action such as click-to-zoom, frequently coupled with relative sizes that require students to mentally visualize the sizes of the objects through proportional reasoning.

Figure 1.

Commonly used expressions of an imperceptible size. The examples in the box are created for the size of a hydrogen atom.


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