Layered Inscriptions: Do They Bridge the Gap between World and Language?

Inscriptions have been the central mediating element in the development of science. They also figure prominently in school science textbooks. However, research suggests that students do not easily understand inscriptions. This may be due to the gap between them and the things in the world that they stand for, which requires tremendous work of the reader. There have been suggestions that overlaying an experience-distant inscription with one that is closer to everyday experience will help students learn. The purpose of this study was to investigate the function of layered inscriptions in middle school science textbooks, which we found to occur 20 and 24 percent of inscriptions in Korean and North American science textbooks, respectively. In this study, we develop a semantic model that allows us to describe the work of reading and interpreting layered inscriptions. Our analyses of several layered inscriptions articulates the tremendous amount of work that needs to be done to establish the links between the layered inscriptions, and between the inscriptions and the world familiar to the student. In addition, different functional relations in layered inscription require different kind and amount of linking work. Our study shows that although layered inscriptions decrease the gaps between more experience-distant inscriptions and the world of experience, the total number of different types of work (structuring, transposing, and translating) to be done and aligned increases. Our study provides a framework for studying how students learn from using inscriptions in general and layered inscriptions in particular. Layered inscriptions 1 Inscriptions are perhaps the most salient feature of science, both in its processes, where inscriptions are created, and its products, such as the inscriptions that appear in published articles and textbooks (Lynch & Woolgar, 1990). Historically, inscriptions constituted resources that allowed science to evolve into the form that we know it today (Edgerton, 1985). It therefore does not come as a surprise that inscriptions are important features of school science textbooks (Roth & McGinn, 1998). But it is surprising that students find it difficult reading and understanding inscriptions (Schnotz, 1993), for one would expect schools in general and science teachers in particular to focus on inscription-relevant literacy skills (Roth, 2002). It would be too quick, however, to fault students or their teachers for these problems. Close analyses of inscriptions in high school textbooks showed that reading inscriptions such as graphs (Roth, Bowen, & McGinn, 1999) or photographs (Pozzer & Roth, 2003) and integrating them with textual information requires a tremendous, perhaps insurmountable amount of work. On the one hand, students may not have had the resources for doing such work; on the other hand, textbook authors may not have done enough to facilitate doing this work. How might textbook authors facilitate students’ efforts in reading inscriptions? A hint for how this might be achieved comes from research on the use of inscriptions in computing environments (e.g., Roschelle, 1992; Roth, Woszczyna, & Smith, 1996). These studies showed that inscriptions of different types presented simultaneously on top of one another, such as simulated objects and vectors that represent force and velocity, mediated the learning of kinematics. Questions seem to impose themselves: “How might the layering of inscriptions provide students with resources in learning science from textbooks?” and “Why might any such mediation occur?” For example, one might ask, “What is the work of reading required to understand an inscription that layers a graph displaying Boyle’s law, naturalistic renderings of pistons, and force arrows?” (Figure 1); and “What does the layering do that other forms of inscriptions do not achieve?” We begin by answering the question, “What work is required for reading these inscriptions?” The text accompanying this figure indicates that the figure represents the relationship between the volume and pressure of a gas, that is, Boyle’s law. Boyle’s law is articulated in terms of the Layered inscriptions 2 statement “at the same temperature, the volume of same amount of gas is inversely dependent to the pressure” and the equation “P * V = k.” The figure itself presents a graph, seemingly torn from a textbook, superposed by two different types of inscriptions. First, there are naturalistic drawings rendering grey weights (or pistons) in a green but apparently transparent beaker. Second, there are three yellow and orange arrows of different length positioned above each beaker-piston combination. Fine arrows in black begin each at a different point on the graph and point to one of the three beakers. The stated purpose of the inscription is to allow students to learn Boyle’s law (as in the mathematical inscription P * V = const), embodied in the graph; not stated is the fact that students need to ground the inscription in their lived experience and understanding of how the world works. What is the work of reading required to relate this layered inscription to one’s lived experience, and therefore to learn from reading or interpreting this inscription? How does this work differ from other circumstances that either state Boyle’s law simply in its mathematical or in mathematical and graphical form? Figure 1. This example of a layered inscription was taken from a Korean seventh-grade textbook in the section on Boyle’s law. The label on the ordinate is “volume (V)”; the label on the abscissa is “pressure (P).” The letters on the graph are “a,” “b,” and “c,” respectively, from top left to bottom right. From Lee, Chae et al., 2000, p.116, reprinted with permission) At a global level, the inscription was designed to mediate students’ learning of Boyle’s law, normally stated in the form of “P * V = k,” and often expressed in terms of a graph. The beakerLayered inscriptions 3 piston combinations and yellow-orange arrows are additional resources that potentially mediate between the more experience-distant equation and graph and the experientially nearer beakerpiston combination. Although this inscription might look easy to the science educator (teacher) who already knows it and knows about Boyle’s law, it is rather complex requiring work that is hidden. Our initial textual presentation of the inscription already articulates the first type of work to be done. That is, at a global level readers have to perceive the three types of inscriptions as separated yet connected inscriptions, constituted at the micro-level by colored dots on the page: the red graph on light-blue lined paper, grey pistons in green beakers, and yellow-orange arrows. At a more fine-grained level, readers have to articulate, for example, the green areas as beakers and the grey areas as pistons or weights. Here already we encounter more work to be done: are these grey entities generic pistons or are they specific weights? More work is required, for example, in the form of comparing the three beaker-piston combinations, which is work within the same type of inscription. Comparing the three pistons reveals that they are equal in size; they are, however, inserted into the beaker at different depths. In fact, for our reading to take us to Boyle’s law, we need to see (perceptual work) the amount of space left on the bottom of the beaker rather than how far the piston has descended into the beaker. That is, if they do represent weights, then our experiences suggest them to be of the same weight—unless they were made of different materials (which requires experiences with and understanding of density). Perceptual structuring further reveals that the three pistons are inserted into the beaker at different heights. Comparison (work) of the different heights with the sameness of the grey parts suggests the latter to be generic pistons (same weights) rather than different weights that would require special attention. These are only drawings of beakers and pistons. Work is required to see the grey part of the drawing as a piston, the green parts of the drawing as a transparent beaker, that is, work is required to relate the drawings to corresponding things in the world we know so well. Even such apparently simple relations between a drawing of a thing and the thing that it denotes—iconic Layered inscriptions 4 relations in the language of semiotics—are learned and culturally specific. They require previous experiences with such things as beakers and pistons (or weights) and with cultural conventions regulating the relationship between drawings and the things they depict. Perceptual structuring (work) reveals that the color of the broad arrow changes from yellow at the tail to orange at the tip. Within-inscription-type comparison (work) reveals that the three arrows have the same width but are different in length. Between-inscription-type comparison (work) is required to produce the inverse relation between the length of the arrow, on the one hand, and the distance of the piston from the bottom of the beaker, on the other hand. Perceptual structuring distinguishes the paper and grid (here blue) from the graph proper, here black axes and red line. The black lines are not just axes but, as indicated by the arrows, are ordinate and abscissa of a grid system where distance from the intersection is equivalent to magnitude. Thus, although not specified in the inscription, a relationship to algebra and the size of numbers needs to be made. The red line has to be articulated (work) as part of this grid rather than of other parts of the inscription. It moves from top left to bottom right in a smooth curve. Each point has to be constructed (work) as a couplet relating a particular value of volume and pressure. (This also requires “pressure” and “volume” to be associated with abscissa and ordinate, respectively.) On the red line, there are three blue circles; these require perc